Bearing unit for wheel and method of manufacturing the bearing unit

ABSTRACT

Respective constituent members of a wheel bearing unit  5  are assembled and also a cover  74  is fixed to an inner end portion of an outer ring  6 . The wheel bearing unit  5  is fitted to a turning machine  38  in a state that a space in which an encoder  72  is provided is sealed tightly from an outside by fitting a stop plug  96  into an insertion hole  84  provided in the cover  74 . A top end portion of a rotating shaft  40  of a turning machine  38  is engaged with an engaged concave portion  102  provided to a hub  8   a . A turning process is applied to an outer side surface of a rotary flange  13  while turning the hub  8   a  around the outer ring  6  by the rotating shaft  40 , and thus the outer side surface is processed in predetermined shape and dimension.

TECHNICAL FIELD

The present invention relates to a wheel bearing unit for supportingrotatably a wheel on a suspension system in a state that such bearingunit bears and fixes a braking rotation body such as a rotor, a drum, orthe like, and improvements in a method of manufacturing such wheelbearing unit.

BACKGROUND ART

According to a configuration shown in FIG. 21, for example, a wheel 1constituting a wheel of a car and a rotor 2 constituting a disc brake asa braking system are supported rotatably on a knuckle 3 constituting asuspension system. More particularly, an outer ring 6 as a stationaryring, which constitutes a wheel bearing unit 5, is fitted into acircular bearing hole 4 formed in the knuckle 3 and then fixed by aplurality of bolts 7. Meanwhile, the wheel 1 and the rotor 2 arecoupled/fixed to a hub 8, which constitutes the wheel bearing unit 5, bya plurality of studs 9 and nuts 10.

Double row outer ring raceways 11 a, 11 b serving as a stationaryraceway respectively are formed on an inner peripheral surface as astationary peripheral surface of the outer ring 6, and a stationaryflange 12 is formed on an-outer peripheral surface. Such outer ring 6 isfixed to the knuckle 3 by coupling the stationary flange 12 to theknuckle 3 via the bolts 7.

In contrast, a rotary flange 13 is formed on a part of an outerperipheral surface of the hub 8, which is projected from an outer endopening of the outer ring 6 (Here, the outside in the axial directionmeans the outside portion in the width direction in a fitted state to acar, and corresponds to the left side in respective FIGS. except FIGS. 23, 6, 7, 9, 18. In contrast, the right side in respective FIGS. exceptFIGS. 2 3, 6, 7, 9, 18, which is located on the center side in the widthdirection in a fitted state to a car, is defined as the inside in theaxial direction). The wheel 1 and the rotor 2 are coupled/fixed to oneside surface (an outer side surface in an illustrated example) of therotary flange 13 by the studs 9 and nuts 10. Also, an inner ring raceway14 a as the rotary raceway is formed on a middle portion of an outerperipheral surface of the hub 8 to oppose to the outside outer ringraceway 11 a out of the double row outer ring raceways 11 a, 11 b. Then,an inner ring 16 constituting a rotating member 23 as a rotary ringtogether with the hub 8 is fitted onto a small-diameter stepped portion15 that is formed on an outer peripheral surface of an inner end portionof the hub 8. Then, an inner ring raceway 14 b is formed on an outerperipheral surface of the inner ring 16 as the rotary raceway to opposeto the inside outer ring raceway 11 b out of the double row outer ringraceways 11 a, 11 b. Here, the outer peripheral surfaces of the hub 8and the inner ring 16 correspond to a rotary peripheral surface setforth in claims.

A plurality of balls 17, 17 serving as a rolling element respectivelyare provided rollably between the outer ring raceways 11 a, 11 b and theinner ring raceways 14 a, 14 b in a state that these balls are held bycages 18, 18 respectively. According to this configuration, a double rowangular contact ball bearing can be constructed in a back-to-backarrangement style, and thus the rotating member 23 is borne rotatably onthe inside of the outer ring 6 to support the radial load and the thrustload. Then, seal rings 19 a, 19 b for isolating an internal space 26, inwhich the balls 17, 17 are provided, from the outside are providedbetween inner peripheral surfaces of both end portions of the outer ring6 and the outer peripheral surface of the middle portion of the hub 8and the outer peripheral surface of the inner end portion of the innerring 16 respectively. Then, since an illustrated example gives the wheelbearing unit 5 that supports the driven wheel (the rear wheel of the FRcar and the RR car, the front wheel of the FF car, all wheels of the 4WDcar), a spline hole 20 is formed in the center portion of the hub 8.Then, a spline shaft 22 of a constant velocity joint 21 is inserted intothis spline hole 20.

In using such wheel bearing unit 5, as shown in FIG. 21, the outer ring6 is fixed to the knuckle 3 and also the wheel 1, on which a tire (notshown) is fitted, and the rotor 5 are fixed to the rotary flange 13 ofthe hub 8. Also, a combination of the rotor 2 and a support member and acaliper (both not shown) fixed to the knuckle 3 constitutes the brakingdisc brake. In the braking operation, a pair of pads that are providedto put the rotor 2 therebetween are pushed against both side surfaces ofthe rotor 2 serving as braking friction surfaces. Here, in thisspecification, the braking friction surface signifies a side surface ofthe rotor in the axial direction when the braking rotation body iscomposed of the rotor, while the braking friction surface signifies aninner peripheral surface of the drum when the braking rotation body iscomposed of the drum.

Meanwhile, it is known that the vibration called the shudder thatentails an unpleasant noise is often generated in the braking operationof the car. As the cause of such vibration, various factors such as anuneven friction condition between a side surface of the rotor 2 and alining of the pad, and the like are known. Also, it is known that therun-out of the rotor 2 acts as the major cause. In other words, the sidesurface of the rotor 2 must be set essentially at a right angle to acenter of rotation of the rotor 2, nevertheless it is difficult to makea complete right angle due to the inevitable manufacturing error, and soon. As a result, it is inevitable that, though its amount is quitesmall, the side surface of the rotor 2 swings in the rotating shaftdirection (the lateral direction in FIG. 21) during the running of thecar. In case such swing (an amount of displacement in the lateraldirection in FIG. 21) is increased, the shudder is caused when thelinings of a pair of pads are thrust against both side surfaces of therotor 2 to brake. Also, in case the drum constituting the drum brake isfixed to the side surface of the rotary flange 13, the vibration likethe shudder is also caused when the brake shoes are pushed against theinner peripheral surface in the situation that this inner peripheralsurface of the drum is not completely parallel with a center of rotationof the drum.

In order to suppress the shudder generated due to such causes, it isimportant to suppress (improve) the swing of the side surface of therotor 2 in the axial direction (axial swing) or the swing of the innerperipheral surface of the drum in the radial direction. For example, inPatent Literatures 1, 2, a method of manufacturing the wheel bearingunit that takes account of the swing of the braking friction surface ofthe braking rotation body such as the rotor 2, or the like is set forth.In the case of the method of manufacturing the wheel bearing unit setforth in Patent Literature 1, when one side surface of the rotary flangeprovided to the outer peripheral surface of the hub is processed intopredetermined shape and dimension, first respective constituent membersof the wheel bearing unit including the hub whose one side surface isnot processed yet are assembled. Then, while rotating the hub by thespindle that is inserted into the inside of the hub in the situationthat the end portion of the outer ring is clamped by the chuck of theprocessing machine, one side surface of the rotary flange provided tothe outer peripheral surface of this hub is finished to thepredetermined shape and dimension by putting the grinding tool onto thisone side surface. In the case where the wheel bearing unit ismanufactured by such method, a perpendicularity of one side surface ofthe rotary flange to a center of rotation of the hub can be improvedirrespective of a dimensional error or an assembling error that isinevitable in manufacturing respective constituent members. Thus, theswing of the braking friction surface of the braking rotation body suchas the rotor, or the like fixed to this one side surface can besuppressed to some extent.

Also, in the case of the method of manufacturing the wheel bearing unitset forth in Patent Literature 2, the hub is rotated by the spindle thatis inserted into the inside of this hub in the situation that the rotoris fixed to one side surface of the rotary flange provided to the outerperipheral surface of the hub. Then, while rotating the hub, respectiveportions are finished into predetermined shape and dimension by puttingthe cutting tool onto both side surfaces of the rotor and a portion ofthe outer peripheral surface of the hub, onto which the inner ring isfitted. In the case where the wheel bearing unit is manufactured by suchmethod, a perpendicularity of the braking friction surface provided toboth side surfaces of the rotor to a center of rotation of the hub canbe improved regardless of the dimensional error or the assembling errorthat is inevitable in manufacturing respective constituent members.Thus, the swing of this rotor can be suppressed to some extent. In thiscase, as the prior art literatures that are associated with the presentinvention, there exist Patent Literatures 3 to 8 in addition to abovePatent Literatures 1, 2.

[Patent Literature 1]

U.S. Pat. No. 6,415,508 Specification

[Patent Literature 2]

U.S. Pat. No. 5,842,388 Specification

[Patent Literature 3]

JP-A-2000-227132 Gazette

[Patent Literature 4]

JP-A-2001-318105 Gazette

[Patent Literature 5]

JP-A-11-83881 Gazette

[Patent Literature 6]

U.S. Pat. No. 6,364,426 Specification

[Patent Literature 7]

U.S. Pat. No. 6,071,180 Specification

[Patent Literature 8]

U.S. patent application Publication No. 2002/0066185

Specification

In recent years, in order to get a rotation speed signal used to operatethe anti-lock brake system (ABS) or the traction control system (TCS),the rotation speed sensing device is incorporated into the above wheelbearing unit. For example, in the configuration shown in FIG. 21, insome case an encoder consisting of a permanent magnet is fitted/fixedonto an end portion of the inner ring 16 rotated together with thewheel, and also a rotation speed sensor is fitted to either the outerring 6 or a part of the member such as the knuckle 3, or the like fixedto this outer ring 6 such that a sensing portion of the sensor opposesto a sensed portion of the encoder. In such configuration, from aviewpoint of assuring a sensing performance (reliability) of therotation speed sensor, it is necessary to prevent the foreign mattersuch as a magnetic powder, or the like from adhering the sensed portionof the encoder. In contrast, in the case of the method of manufacturingthe wheel bearing unit set forth in above Patent Literatures 1, 2, it isnot considered at all that the encoder is fixed to the hub constitutingthe rotating member or the inner ring. For this reason, a followingdisadvantage {circle around (1)} is caused when the encoder is providedto the wheel bearing unit set forth in above Patent Literatures 1, 2.

{circle around (1)} Upon grinding or cutting either one side surface ofthe rotary flange or the braking friction surface of the brakingrotation body such as the rotor, or the like couple/fixed to this oneside surface to improve a perpendicularity of the braking frictionsurface of the rotor to the center of rotation of the hub, it ispossible that chips as the magnetic material generated by this grindingor cutting adhere to the sensed portion of the encoder. In case thechips adhere in this manner, a sensing performance of the rotation speedsensor becomes worse in the wheel bearing unit into which the rotationspeed sensing device is incorporated.

Also, in the case of the method of manufacturing the wheel bearing unitset forth in above Patent Literatures 1, 2, a following disadvantage{circle around (2)} is present respectively.

{circle around (2)} First, in the case of the configuration set forth inabove Patent Literature 1, there exists the dimensional error or theassembling error that is inevitable in manufacturing between the sidesurface of the rotary flange provided to the outer peripheral surface ofthe hub and the side surface of the braking rotation body such as therotor, or then like fixed to this side surface. Therefore, it isdifficult to say that the swing of the braking friction surface of thebraking rotation body can be suppressed satisfactorily. Then, in thecase of the method of manufacturing the wheel bearing unit set forth inabove Patent Literature 2, there exists the dimensional error or theassembling error that is inevitable in manufacturing a plurality ofparts that are located between the knuckle constituting the suspensionsystem and the portion, on which the inner ring is fitted, of the outerperipheral surface of the hub. Therefore, it is also difficult to saythat the swing of the side surface of the braking rotation body can besuppressed satisfactorily. Here, in Patent Literature 3, the measure toregulate a degree of instability of the side surface of the rotor fixedto the rotary flange, which is provided to the outer peripheral surfaceof the hub, while the hub constituting the wheel bearing unit is rotatedaround the outer ring is set forth. However, in this Patent Literature3, a method of manufacturing the wheel bearing unit in which a degree ofinstability of the side surface is regulated is not set forth at all.

DISCLOSURE OF THE INVENTION

In light of such circumferences, a wheel bearing unit and a method ofmanufacturing the same of the present invention have been invented toovercome at least the disadvantage {circle around (1)} out of the abovedisadvantages {circle around (1)}{circle around (2)}.

Out of the wheel bearing units and the methods of manufacturing the sameof the present invention, like the foregoing wheel bearing unit in theprior art, a wheel bearing unit set forth in claims 1 and 2 includes astationary ring that has a stationary raceway on a stationary peripheralsurface and is not rotated in operation, a rotary ring that has a rotaryraceway on a rotary peripheral surface and is rotated in operation, aplurality of rolling elements provided between the stationary racewayand the rotary raceway, and a rotary flange provided to an outerperipheral surface of the rotary ring. Also, the wheel bearing unitcouples/supports a braking rotating body having a braking frictionsurface against which a friction material is pushed in a brakingoperation onto a side surface of the rotary flange at least inoperation.

In particular, in the wheel bearing unit set forth in claim 1, anencoder which is fixed to a part of the rotary ring and at least a partof which is made of a permanent magnet is provided. Also, the sidesurface of the rotary flange is processed into predetermined shape anddimension while rotating the rotary ring around the stationary ring in astate that the stationary ring, the rotary ring, and the plurality ofrolling elements are assembled together and also a space in which theencoder is provided is isolated from an outside by fitting a stop plugor a cover to a part of the stationary ring or the rotary ring directlyor via other member. Also, the stop plug or the cover is removed fromthe stationary ring or the rotary ring after the side surface of therotary flange is processed into predetermined shape and dimension butbefore the wheel bearing unit is fitted to a suspension system.

Also, in the wheel bearing unit set forth in claim 2, an encoder whichis fixed to a part of the rotary ring and at least a part of which ismade of a permanent magnet is provided. Also, the braking frictionsurface of the braking rotating body is processed into predeterminedshape and dimension while rotating the rotary ring that couples/supportsthe braking rotating body around the stationary ring in a state that thestationary ring, the rotary ring, and the plurality of rolling elementsare assembled together and also a space in which the encoder is providedis isolated from an outside by fitting a stop plug or a cover to a partof the stationary ring or the rotary ring directly or via other member.Also, the stop plug or the cover is removed from the stationary ring orthe rotary ring after the braking friction surface is processed intopredetermined shape and dimension but before the wheel bearing unit isfitted to a suspension system.

In addition, in a method of manufacturing a wheel bearing unit set forthin claim 4 that corresponds to a method of manufacturing the wheelbearing unit according to claim 1, the side surface of the rotary flangeis processed into predetermined shape and dimension while rotating therotary ring around the stationary ring in the state that the stationaryring, the rotary ring, and a plurality of rolling elements are assembledtogether and also the space in which the encoder is provided is isolatedfrom the outside by fitting the stop plug or the cover to a part of thestationary ring or the rotary ring directly or via other member. Then,the stop plug or the cover is removed from the stationary ring or therotary ring before the wheel bearing unit is fitted to the suspensionsystem.

Further, in a method of manufacturing a wheel bearing unit set forth inclaim 5 that corresponds to a method of manufacturing the wheel bearingunit according to claim 2, the braking friction surface of the brakingrotating body is processed into predetermined shape and dimension whilerotating the rotary ring that couples/supports the braking rotating bodyaround the stationary ring in a state that the stationary ring, therotary ring, and the plurality of rolling elements are assembledtogether and also the space in which the encoder is provided is isolatedfrom the outside by fitting the stop plug or the cover to a part of thestationary ring or the rotary ring directly or via other member. Then,the stop plug or the cover is removed from the stationary ring or therotary ring before the wheel bearing unit is fitted to the suspensionsystem.

According to the wheel bearing unit and the method of manufacturing thesame of the present invention constructed as above, in order to improvea perpendicularity or a parallelism of the braking friction surface to acenter of rotation of the rotary ring in the configuration in which theencoder is fitted to the rotary ring, either the side surface of therotary flange or the braking friction surface is processed into thepredetermined shape and dimension in a state that the constituentmembers including the rotary ring and the encoder are assembled,nevertheless it can be prevented that the chips generated in thisprocess adhere to the sensed portion of the encoder. Therefore, asensing performance (reliability) of the rotation speed sensor that isopposed to the sensed portion can be ensured sufficiently. Also, sincethe stop plug or the cover is removed from a part of the stationary ringor the rotary ring immediately before the wheel bearing unit is fittedto the suspension system, adhesion of the foreign matter such as themagnetic powder, or the like onto the sensed portion can be preventedfrom this fitting of the stop plug or the cover to this removal whilethe wheel bearing unit is carried, or the like. Also, since the stopplug or the cover is removed from the stationary ring or the rotary ringafter the side surface of the rotary flange or the braking frictionsurface is processed but before the wheel bearing unit is fitted to thesuspension system, such stop plug or such cover offers no obstruction tothe operation of assembling the rotation speed sensor into the wheelbearing unit or fitting the wheel bearing unit to the vehicle.

In this event, in Patent Literature 4, such a configuration is set forththat the cover formed like a bottomed circular cylinder is fitted/fixedonto the inner end portion of the outer ring as the stationary ring andalso the space in which the encoder is provided is isolated from theoutside by fitting the detachable stop plug into the insertion holeprovided in a part of the cover. Also, in Patent Literature 5, such aconfiguration is set forth that the space in which the encoder isprovided is isolated from the outside by fitting the detachable stopplug into the insertion hole provided in a part of the outer ring as thestationary ring. However, in both of above Patent Literature 4, 5, suchan approach is not set forth that either the side surface of the rotaryflange or the braking friction surface of the braking rotation bodyfixed to this side surface is processed into the predetermined shape anddimension while rotating the rotary ring with respect to the stationaryring in the situation that the stationary ring, the rotary ring, and aplurality of rolling elements are assembled and then the space in whichthe encoder is provided is isolated from the outside by fitting the stopplug into a part of the stationary ring or the rotary ring directly orvia other member. Also, in both of above Patent Literature 4, 5, such anapproach is not set forth that the stop plug is removed from thestationary ring or the rotary ring after either the side surface of therotary flange or the braking friction surface is processed into thepredetermined shape and dimension but before the wheel bearing unit isfitted to the suspension system.

In addition, according to the wheel bearing unit set forth in claim 2and a method of manufacturing the wheel bearing unit set forth in claim5, when the braking friction surface of the braking rotation body isprocessed in the predetermined shape and dimension, such an event can beeliminated that the dimensional error or the assembling error that isinevitable in manufacturing a plurality of parts that are locatedbetween a part of the suspension system and the braking rotation bodyleads to the worsening of a perpendicularity or a parallelism of thebraking friction surface to a center of rotation of the rotating shaft.Therefore, the swing of the braking friction surface can be suppressedsufficiently. Also, since there is no necessity to improve particularlya dimensional accuracy of a plurality of parts, a cost required tosuppress the swing of the braking friction surface can be suppressedsufficiently low.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a first embodiment of the presentinvention in a state that a cover is fixed to an inner end portion of anouter ring and also a stop plug is inserted/fixed into an insertion holeprovided in this cover;

FIG. 2 is a perspective view showing only the stop plug;

FIG. 3 is a perspective view of a holder that is fitted to a structurein the first embodiment;

FIG. 4 is a sectional view showing the first embodiment in a state thata turning process is applied to an outer side surface of a rotaryflange;

FIG. 5 is a sectional view showing a second embodiment of the presentinvention in a state that the turning process is applied to the outerside surface of the rotary flange;

FIG. 6 is an enlarged sectional view of an A portion;

FIG. 7 is a sectional view showing a deformed state caused when the stopplug is removed in the second embodiment;

FIG. 8 is a sectional view showing a third embodiment of the presentinvention in a state that a cover is fixed to an inner end portion of aspline hole provided in a hub;

FIG. 9 is a schematic sectional view taken along a B-B line;

FIG. 10 is a sectional view showing a fourth embodiment of the presentinvention in a state that the cover is fixed to an inner end portion ofan outer ring;

FIG. 11 is a sectional view showing a fifth embodiment of the presentinvention in a state that the turning process is applied to the outerside surface of the rotary flange;

FIG. 12 is a sectional view showing a sixth embodiment of the presentinvention in a state that the turning process is applied to the outerside surface of the rotary flange;

FIG. 13 is a sectional view showing a seventh embodiment of the presentinvention in a state that the cover is fixed to the inner end portion ofthe outer ring before a rotor is fixed to the rotary flange;

FIG. 14 is a sectional view showing the seventh embodiment similarly ina state that the turning process is applied to both side surfaces and anouter peripheral surface of the rotor;

FIG. 15 is a sectional view showing an eighth embodiment of the presentinvention, which is similar to FIG. 13;

FIG. 16 is a sectional view showing the eighth embodiment, which issimilar to FIG. 14;

FIG. 17 is a sectional view showing a ninth embodiment of the presentinvention in a state that the cover is fixed to the inner end portion ofthe hub before the rotor is fixed to the rotary flange;

FIG. 18 is a view showing only the cover, when viewed from the left sidein FIG. 17;

FIG. 19 is a sectional view showing a tenth embodiment of the presentinvention in a state that the cover and the stop plug are fitted to theinner end portion of the hub and the insertion hole provided to theouter ring respectively before the rotor is fixed to the rotary flange;

FIG. 20 is a sectional view showing an eleventh embodiment of thepresent invention in a state that the cover is fixed to the inner endportion of the outer ring before the rotor is fixed to the rotaryflange; and

FIG. 21 is a sectional view showing a first embodiment of a fitted stateof a wheel bearing unit as a subject of the present invention.

In above FIGS., a reference numeral 1 denotes a wheel, 2 rotor, 3knuckle, 4 bearing mounting hole, 5 wheel bearing unit, 6, 6 a, 6 b, 6 couter ring, 7 bolt, 8, 8 a, 8 b hub, 9 stud, 10 nut, 11 a, 11 b outerring raceway, 12, 12 a stationary flange, 13 rotary flange, 14 a, 14 binner ring raceway, 15 small-diameter stepped portion, 16, 16 a, 16 binner ring, 17 ball, 18 cage, 19 a, 19 b seal ring, 20 spline hole, 21constant velocity joint, 22 spline shaft, 23, 23 a, 23 b rotatingmember, 24 caulked portion, 25 fitting hole, 26 internal space, 27slinger, 28 encoder, 29 small-diameter stepped portion, 30, 30 a to 30 fcover, 31 cylinder portion, 32 bottom plate portion, 33 threaded hole,34 through hole, 35 tentatively setting screw, 36 large-diametercircular cylinder portion, 37 stepped surface, 38, 38 a, 38 b turningmachine, 39 chuck, 40, 40 a rotating shaft, 41 a, 41 b, 41 c precisionmachining tool, 42 reinforcing member, 43 elastic member, 44 fittingportion, 45 through hole, 46 circular ring portion, 47 cylinder portion,48 curved portion, 49 hydraulic cylinder, 50 fitted cylinder portion, 51pressing collar portion, 52 projected portion, 53 female spline portion,54 cylinder portion, 55 latching collar portion, 56 insertion hole, 57cover, 58 outer-diameter-side cylinder portion, 59 collar portion, 60inner-diameter-side cylinder portion, 61 stop plug, 62large-diameter-side cylinder portion, 63 small-diameter-side cylinderportion, 64 stepped portion, 65 bottom plate portion, 66 annular piston,67 taper portion, 68 lip portion, 69 outer-diameter-side cylinderportion, 70 supporting ring, 71 cylinder portion, 72 encoder, 73small-diameter stepped portion, 74 cover, 75 main body, 76 fittingcylinder, 77 fitting cylinder portion, 78 inward-directed collarportion, 79 cylinder wall portion, 80 fitting groove, 81 O ring, 82bottom plate portion, 83 projected portion, 84 insertion hole, 85holder, 86 inserted portion, 87 fitting flange portion, 88 harness, 89fitting groove, 90 through hole, 91 core metal, 92 nut, 93 internalthread portion, 94 engaging teeth, 95 circular hole, 96 stop plug, 97small-diameter cylinder portion, 98 large-diameter cylinder portion, 99bottom plate portion, 100 projected stripe portion, 101 stepped portion,102 engaging concave portion, 103 encoder main body, 104 precisionmachining tool, 105 cylinder portion, 106 small-diameter cylinderportion, 107 large-diameter cylinder portion, 108 encoder, 109 insertionhole, 110 stop plug, 111 fitting portion, 112 stopper portion, 113 knobportion, 114 cylinder portion, 115 bottom plate portion, 116 chamferedportion, 117 small-diameter cylinder portion, 118 large-diametercylinder portion, 119 stepped portion, 120 bottom plate portion, 121taper portion, 123 taper portion, 124 threaded hole, and 125 projectedportion.

BEST MODE FOR CARRYING OUT THE INVENTION

FIGS. 1 to 4 show a first embodiment of the present invention, whichcorresponds to claims 1, 3, 4, and 6. In the wheel bearing unit 5produced by the manufacturing method in this example, the stationaryflange 12 used to couple/fix the outer ring 6 to the knuckle 3 (see FIG.21) is provided to the middle portion of the outer peripheral surface ofthe outer ring 6 as the stationary ring. Also, the double row outer ringraceways 11 a, 11 b serving as the stationary side raceway respectivelyare formed on the inner peripheral surface as the stationary peripheralsurface of the outer ring 6. Also, a small-diameter stepped portion 29is formed on an inner half portion, which is deviated inward from theinner side surface of the stationary flange 12, of the outer peripheralsurface of the outer ring 6.

Also, the inner ring raceways 14 a, 14 b serving as the rotary racewayrespectively are formed on portions, which oppose to the outer ringraceways 11 a, 11 b, of the outer peripheral surfaces as the rotaryperipheral surfaces of a hub 8 a and the inner ring 16 constituting arotating member 23 a as the rotary ring respectively. In other words,the inner ring raceway 14 a is formed directly on the middle portion ofthe outer peripheral surface of the hub 8 a, and also the inner ring 16on the outer peripheral surface of which the inner ring raceway 14 b isformed is fitted onto the small-diameter stepped portion 15 formed onthe innermost portion of the hub 8 a. Also, in order to prevent that theinner ring 16 gets out of the small-diameter stepped portion 15, acaulked portion 24 is formed on the inner end portion of the hub 8 a. Inother words, the inner ring 16 is fitted onto the small-diameter steppedportion 15 and then the caulked portion 24 is formed by plasticallydeforming a cylinder portion 71, which is provided to the inner endportion of the hub 8 a to protrude from the inner end surface of theinner ring 16, outward in the radial direction. Thus, the inner endsurface of the inner ring 16 is pressed by the caulked portion 24.According to this configuration, the inner ring 16 is fitted/fixed ontothe inner end portion of the hub 8 a. Then, a plurality of balls 17, 17serving as the rolling element respectively are provided rollablybetween the outer ring raceways 11 a, 11 b and the inner ring raceways14 a, 14 b.

Also, unlike the case of the conventional structure shown in above FIG.21, the wheel bearing unit in the present embodiment is used to bear thewheel used to as the nondriven wheel (the front wheel of the FR car andthe RR car, the rear wheel of the FF car). For this reason, the splinehole 20 (see FIG. 21) that passes through the hub 8 a in the axialdirection is not formed in the hub 8 a.

Also, the rotary flange 13 to which the wheel 1 (FIG. 21) constitutingthe wheel and the rotor 2 as the braking rotation body are fixed isprovided to a near-outer-end portion of an outer peripheral surface ofthe hub 8 a, which is projected from an outer end opening of the outerring 6. A threaded hole 124 is formed at plural locations in thecircumferential direction of the rotary flange 13 respectively on thesame circumference that has a center of rotation of the hub 8 a as itscenter. Then, thread portions provided to front half portions of aplurality of studs (not shown) can be screwed into these threaded holes124 respectively. The wheel 1 and the rotor 2 (see FIG. 21) are heldbetween head portions provided to based end portions of respective studsand the outer side surface of the rotary flange 13 in the situation thatrespective studs are screwed into respective threaded holes 124. Withthis configuration, unlike the case of the conventional structure shownin above FIG. 21, the nuts are not needed to couple/fix the wheel 1 andthe rotor 2 to the rotary flange 13 (see FIG. 13). Also, it is possibleto prevent the situation that the studs will be a hindrance in theturning operation of the outer side surface of the rotary flange 13 orthe outer side surface is distorted when the studs arepress-fitted/fixed to the inside of the fitting hole. Also, in the caseof this embodiment, an engaged concave portion 102 with which a top endportion of a rotating shaft 40 (FIG. 4) of a turning machine 38described later is engaged is formed on the inside of a center portionof an outer end surface of the hub 8 a. This engaged concave portion 102has a hexagonal cross section and is formed by the forging.

Meanwhile, an encoder 72 is fitted/fixed onto the inner end portion ofthe inner ring 16. This encoder 72 has a supporting ring 70 and anencoder main body 103. The supporting ring 70 is formed like an annularring having an almost T-shaped cross section as a whole by folding amagnetic metal plate such as a SPCC, or the like, and then isfitted/fixed onto the inner end portion of the inner ring 16 as aninterference fit. Then, the encoder main body 103 is attached to theinner side surface of the supporting ring 70 by bonding, or the like.This encoder main body 103 is made of a rubber into which ferritepowders are mixed, for example, and is magnetized in the axialdirection. Also, the magnetizing direction is changed alternately at anequal interval in the circumferential direction. Thus, the S pole andthe N pole are arranged alternately at an equal interval in thecircumferential direction on the inner side surface of the encoder mainbody 103. The reason why the supporting ring 70 is formed to have thealmost T-shaped cross section as mentioned above is that magnetizedareas of respective magnetic poles (the N pole and the S pole) of theencoder main body 103 is increased by reducing an inner diameter of theencoder main body 103 smaller than an outer diameter of a shoulderportion of the inner ring 16. Thus, magnetic flux density at therotation speed sensor using the encoder main body 103 as the sensedportion can be improved because the magnetized areas of respectivemagnetic poles of the encoder main body 103 are increased.

In the case of the present embodiment, a small-diameter stepped portion73 is formed on the outer peripheral surface of the inner end portion ofthe inner ring 16. Since the small-diameter stepped portion 73 isformed, the distortion of the inner ring raceway 14 b provided on theouter peripheral surface of the inner ring 16 can be preventedindependently of an outward-directing force that is applied to the innerend portion of the inner ring 16 when the cylinder portion 71 providedto the inner end portion of the hub 8 a is plastically deformed outwardin the diameter direction. In this case, if the distortion of the shapeof the small-diameter stepped portion 73 is small, the supporting ring70 can also be fitted onto the small-diameter stepped portion 73.

Also, in the case of the present embodiment, the seal ring 19 a isprovided between the inner peripheral surface of the outer end portionof the outer ring 6 and the outer peripheral surface of the middleportion of the hub 8 a. In contrast, a cover 74 is put on the openingportion of the inner end of the outer ring 6. The cover 74 consists of amain body 75 formed like a cylinder with a bottom by the injectionmolding of synthetic resin, and a fitting cylinder 76 coupled to theopening portion of the main body 75. The fitting cylinder 76 is formedby plastically deforming a metal plate such as a stainless steel plate,or the like having a corrosion resistance. This fitting cylinder 76consists of a fitting cylinder portion 77 formed like an annular ring asa whole to have an L-shaped cross section, and an inward-directed collarportion 78 folded inward from a base end edge of the fitting cylinderportion 77 in the diameter direction. Such fitting cylinder 76 iscoupled to an opening portion of the main body 75 by molding theinward-directed collar portion 78 onto the end portion of the opening ofthe main body 75 at the time of the injection molding of the main body75.

The cover 74 constructed as above is fitted/fixed onto thesmall-diameter stepped portion 29 of the outer ring 6, on the inner endportion of which the fitting cylinder portion 77 is provided, as aninterference fit. Also, an end surface of the opening portion of themain body 75, i.e., a top end portion of a cylinder wall portion 79formed on an outer edge portion of the main body 75 is brought intocontact with the inner end surface of the outer ring 6 in thiscondition. A fitting groove 80 is formed on the top end surface of thecylinder wall portion 79 around the entirety of a circumference, andthen an O ring 81 is fitted into the fitting groove 80. In the conditionthat the top end surface of the cylinder wall portion 79 comes intocontact with the inner end surface of the outer ring 6, this O ring 81is elastically compressed between this inner end surface and a bottomsurface of the fitting groove 80 to tightly seal the couple portionbetween the cover 74 and the outer ring 6.

Also, a projected portion 83 that is projected in the axial direction isprovided to a part of an inner side surface, which is deviated outwardpartially (the upper portion in FIGS. 1 and 4) in the diameterdirection, of a bottom plate portion 82 of the main body 75 constitutingthe cover 74. Also, an insertion hole 84 is provided in a portion of thebottom plate portion 82, which corresponds to the projected portion 83and opposes to an inner side surface of the encoder 72, to pass throughthe bottom plate portion 82 in the axial direction. Thus, an insertedportion 86 of a holder 85 (FIG. 3) for holding the rotation speed sensorcan be inserted into the insertion hole 84.

This holder 85 contains the rotation speed sensor in a synthetic resin.

This holder 85 contains the rotation speed sensor in a synthetic resin.This rotation speed sensor consists of an IC into which a magneticsensing element such as a magnetoresistance element (MR element), or thelike whose characteristic is changed in response to a flow direction andmagnetic of a magnetic flux and a waveform shaping circuit for shapingan output waveform of this magnetic sensing element are incorporated, apole piece made of magnetic material to guide the magnetic flux to themagnetic sensing element, and the like. Also, the holder 85 has theinserted portion 86 at its near- top-end portion and a fitting flangeportion 87 at its base end portion respectively. A sensing portion ofthe rotation speed sensor is positioned on the top end surface portionof the inserted portion 86. Also, an end portion of a harness 88 forsupplying an output signal, which is output as a shaped waveform fromthe IC, to a controller (not shown) is connected to the holder 85directly (without the intervention of the connector, or the like).

Also, a fitting groove 89 is formed on an outer peripheral surface of amiddle portion of the inserted portion 86, and then the O ring (notshown) is fitted in the fitting groove 89. When the inserted portion 86is inserted into the insertion hole 84, this O ring is elasticallycompressed between an inner peripheral surface of the insertion hole 84and a bottom surface of the fitting groove 89 to prevent the foreignmatter such as a muddy water, or the like from entering into the cover74 through this insertion area.

Also, an outer side surface of the fitting flange portion 87 provided tothe base end portion of the holder 85 must come into contact with an endportion of the projected portion 83 provided to the cover 74, so thatmutual contact surfaces of both portions 87, 83 are formed as a flatsurface respectively. Also, a through hole 90 is formed in a top endportion (a lower end portion in FIG. 3) of the fitting flange portion87, and then a cylindrical core metal 91 is inserted into the inside ofthe through hole 90.

Meanwhile, a nut 92 is embedded in a part of the end portion of theprojected portion 83 provided to the cover 74, which is aligned with thethrough hole 90 provided in the holder 85 in a state that the insertedportion 86 provided in the holder 85 is inserted into the insertion hole84 provided in the cover 74. An internal thread portion 93 is formed onan inner peripheral surface of the nut 92, and a plurality of engagingteeth 94, 94 are formed on an outer peripheral surface of the nut 92.Then, this nut 92 is fixed to the cover 74 by pushing the nut 92 into abottomed circular hole 95 in a heated state. This circular hole 95 isprovided beforehand to a part of the end surface of the projectedportion 83 and has an inner diameter that is slightly smaller than adiameter of a circumscribed circle of the nut 92. In this case, this nut92 may be fixed to the cover 74 by molding it together with this cover74 in the injection molding.

In operation of the wheel bearing unit 5, the sensing portion of therotation speed sensor that is provided to the holder 85 held on thecover 74 is opposed to the inner side surface as the sensed portion ofthe encoder 72 via a small clearance. Thus, the output signal of therotation speed sensor, which is changed in response to the rotationspeed of the rotation speed, can be output via the harness 88. Suchencoder 72 and the rotation speed sensor constitute a rotation speedsensing unit that senses the rotation speed of the wheel fixed to thehub 8 a.

In particular, in the case of the wheel bearing unit of the presentinvention, a stop plug 96 shown in detail in FIG. 2 can be detachablyattached into the insertion hole 84 that is provided in the cover 74 toreceive the inserted portion 86 of the holder 85. This stop plug 96 isformed of an inexpensive synthetic resin such as polypropylene (PP),polyethylene terephthalate (PET), or the like by using the injectionmolding. The stop plug 96 has a small-diameter cylinder portion 97 asthe fitted portion, and a large-diameter cylinder portion 98. One end ofthe small-diameter cylinder portion 97 out of them is covered with abottom plate portion 99 (the left end in FIGS. 1 and 2). Also, projectedstripe portions 100, 100 each extended in the axial direction areprovided at plural locations on an outer peripheral surface of a basehalf portion (a right half portion in FIGS. 1 and 2) of thesmall-diameter cylinder portion 97 in the circumferential direction.Because a diameter of a circumscribed circle of these plural projectedstripe portions 100, 100 in their free condition is set slightly largerthan an inner diameter of the insertion hole 84, the small-diametercylinder portion 97 can be fitted into the insertion hole 84 by means ofan interference fit. Also, the stop plug 96 can be positioned to thecover 74 by a stepped portion 101 that connects the small-diametercylinder portion 97 and the large-diameter cylinder portion 98.

Here, the stop plug 96 may be formed of other elastic material such asan elastomer like a rubber, or the like in addition to the abovesynthetic resin.

Also, in the case of the present embodiment, in order to reduce amaterial cost of the stop plug 96, a thickness of the stop plug 96except the large-diameter cylinder portion 98 is set small like 0.5 mmor less. In this case, a too small rigidity caused when a thickness ofthe large-diameter cylinder portion 98 is also reduced makes difficultan operation to attach/detach the stop plug 96 to/from the cover 74 bygripping this large-diameter cylinder portion 98. For this reason, inthe case of the present embodiment, the rigidity of the large-diametercylinder portion 98 is enhanced by increasing a thickness of thelarge-diameter cylinder portion 98 larger than a thickness of otherportions.

Also, in the case of the present invention, the outer side surface ofthe rotary flange 13 provided to the outer peripheral surface of the hub8 a is finished into the predetermined shape and dimension by applyingthe turning process to this outer side surface in a predetermined state.In other words, when the turning process is applied to this outer sidesurface, first respective parts of respective constituent members of thewheel bearing unit 5 are processed into the predetermined shape anddimension in the parts maker that manufactures the wheel bearing unit 5,or the like. Then, respective constituent members of the wheel bearingunit 5 are assembled into a state shown in FIG. 1 in the parts makerthat manufactures the wheel bearing unit 5. In other words, the outerring 6, the hub 8 a, the inner ring 16, and a plurality of balls 17, 17are assembled together in a condition that a plurality of balls 17, 17are provided between the outer ring raceways 11 a, 11 b provided on theinner peripheral surface of the outer ring 6 and the inner ring raceways14 a, 14 b provided on the outer peripheral surfaces of the hub 8 a andthe inner ring 16 respectively. Then, the seal ring 19 a is providedbetween the inner peripheral surface of the outer end portion of theouter ring 6 and the outer peripheral surface of the middle portion ofthe hub 8 a, and also the encoder 72 is provided onto the outerperipheral surface of the inner end portion of the inner ring 16. Then,the cover 74 is fitted onto the outer peripheral surface of the innerend portion of the outer ring 6, and also the small-diameter cylinderportion 97 of the stop plug 96 is fitted/fixed into the insertion hole84 provided in the cover 74 to close the insertion hole 84. In thiscase, an operation to provide the stop plug 96 in the insertion hole 84may be executed before the cover 74 is fitted to the inner end portionof the outer ring 6. In any event, the space in which the encoder 72 isprovided can be isolated from the outside in the state that theinsertion hole 84 is closed by the stop plug 96.

Then, as shown in FIG. 4, the wheel bearing unit 5 in which the turningprocess is applied to the outer side surface of the rotary flange 13 isfitted on the turning machine 38 in this condition. In this case, alarge-diameter circular cylinder portion 36 provided on a portion of theouter peripheral surface of the outer ring 6 between the inner sidesurface of the stationary flange 12 and the small-diameter steppedportion 29 is clamped by top end portions of a chuck 39 constituting theturning machine 38. Then, the top end portions of the chuck 39 are putonto a flat surface portion, which coincides with a virtual flat surfacethat intersects orthogonally with the central axis of the outer ring 6,of the inner side surface of the stationary flange 12. Because the topend portions of the chuck 39 are put onto the inner side surface of thestationary flange 12 in this manner, the wheel bearing unit 5 can befitted easily onto the turning machine 38 in a desired position.

Then, the top end portion, an outer peripheral surface of which isshaped into a hexagon, of the rotating shaft 40 of the turning machine38 is fitted to the engaged concave portion 102 provided in the centerportion of the outer end portion of the hub 8 a. Then, the turningprocess is applied to the outer side surface of the rotary flange 13 byputting a precision machining tool 104 to this outer side surface inthis condition while the hub 8 a is rotated on its central axis byrotating/driving the rotating shaft 40, whereby this outer side surfacecan be finished into the predetermined shape and dimension in this case,the precision machining tool 104 applies the turning process to theouter side surface while moving on the flat surface that intersectsorthogonally with the central axis of rotation of the hub 8 a. Also,while rotating the hub 8 a, another precision machining tool (not shown)is put onto a small-diameter cylinder portion 106, which is provided tothe top half portion, and a large-diameter cylinder portion 107, whichis provided to the bottom half portion, of the outer peripheral surfaceof a cylinder portion 105 that is provided to the outer end surface ofthe hub 8 a to protrude in the axial direction respectivelysimultaneously with the turning process or before or after the turningprocess. This small-diameter cylinder portion 106 is fitted into acircular hole provided to the center portion of the wheel 1 when thewheel 1 (see FIG. 21) constituting the wheel is coupled to the hub 8 a,while this large-diameter cylinder portion 107 is fitted into a circularhole provided to the center portion of the rotor 2 when the rotor 2 (seeFIG. 21) is coupled to the hub 8 a.

Then, the stop plug 96 is removed after the turning process is appliedto the outer side surface of the rotary flange 13 but before the outerring 6 is coupled/fixed to the knuckle 3. In contrast, the cover 74 isstill fixed to the inner end portion of the outer ring 6 after the outerring 6 is coupled/fixed to the knuckle 3. Then, after the outer ring 6is coupled/fixed to the knuckle 3, the holder 85 is coupled/fixed to thecover 74 in a state that the inserted portion 86 of the holder 85 isinserted into the insertion hole 84 provided in the cover 74, wherebythe wheel bearing unit with the rotation speed sensing unit iscompleted.

In the case of the method of manufacturing the wheel bearing unit of thepresent invention and the wheel bearing unit produced by thismanufacturing method, the outer side surface of the rotary flange 13provided to the outer peripheral surface of the hub 8 a is finished intothe predetermined shape and dimension by applying the turning process tothis outer side surface while rotating the hub 8 a with respect to theouter ring 6 in a state that respective constituent members of the wheelbearing unit 5 are assembled together. Therefore, in the case of thepresent invention, it can be eliminated that, when this outer sidesurface is to be processed into the predetermined shape and dimension, adimensional error and a fitting error of respective constituent membersof the wheel bearing unit 5 result in the worsening of aperpendicularity of the outer side surface of the rotary flange 13 to acenter of rotation of the hub 8 a. For this reason, the swing of thebraking friction surface of the rotor 2 fixed to this outer side surfacecan be suppressed.

In addition, in the case of the present embodiment, when the turningprocess is applied to this outer side surface of the rotary flange 13,the cover 74 is fitted/fixed onto the inner end portion of the outerring 6 and then the space in which the encoder 72 is sealed tightly andisolated from the outside by inserting/fixing the stop plug 96 into theinsertion hole 84 provided to this cover 74. Therefore, when the outerside surface of the rotary flange 13 is processed into the predeterminedshape and dimension, the event that the chips generated in this processadhere to the inner side surface of the encoder 72 through the insertionhole 84 can be prevented. As a result, a sensing performance of therotation speed sensor that faces to the inner side surface of theencoder 72 can be assured sufficiently.

Further, according to the present invention, the stop plug 96 may beremoved from the cover 74 fixed to the outer ring 6 immediately beforethe outer ring 6 is coupled/fixed to the knuckle 3. Therefore, while thewheel bearing unit 5 manufactured by the parts maker is carried to thefinished car maker, or the like, adhesion of the foreign matter such asthe magnetic powder, or the like to the inner surface of the encoder 72can be prevented from this fitting of the stop plug 96 to the removalthereof. Also, the stop plug 96 may be removed from the cover 74 afterthe outer side surface of the rotary flange 13 is processed but beforethe outer ring 6 is coupled/fixed to the knuckle 3. Therefore, the stopplug 96 in no way disturbs the fitting of the holder 85, which holds therotation speed sensor, onto the cover 74.

Also, in the case of the present embodiment, the large-diameter circularcylinder portion 36 provided to the outer peripheral surface near theinner end of the outer ring 6 is clamped by the chuck 39 constitutingthe turning machine 38. An improvement of a dimensional accuracy of thelarge-diameter circular cylinder portion 36 can be easily made.Therefore, an operation of putting the wheel bearing unit 5, to theouter side surface of the rotary flange 13 of which the turning processmust be applied, on the turning machine 38 can be easily done.

Next, FIGS.5 to 7 show a second embodiment of the present invention,which also corresponds to claims 1, 3, 4, and 6. A wheel bearing unit ofthe present embodiment is used to bear the wheel that is used as thedriven wheel, unlike the case of the above first embodiment. For thispurpose, the spline hole 20 that passes through the hub 8 in the axialdirection is formed at the center portion of the hub 8. Also, in thecase of the present embodiment, the inner ring 16 is fitted/fixed ontothe inner end portion of the hub 8 by means of the interference fit thatgenerates a larger immobile force than an axial force generated based onthe preload applied to respective balls 17, 17, or the like. Also, anencoder 108 is fitted/fixed onto a part of the outer peripheral surfaceof the middle portion of the hub 8, which is located between the innerring raceway 14 a formed on the outer peripheral surface of the hub 8and the inner ring 16, by means of the interference fit. This encoder108 is constructed by fitting/fixing an encoder main body formed like acircular cylinder onto an outer peripheral surface of a reinforcingmember formed also like a circular cylinder. The reinforcing member ismade of a magnetic metal plate such as a mild steel plate like SPCC, orthe like and formed also like a circular cylinder. Also, the encodermain body is made of a rubber into which ferrite powders are mixed, forexample, and is magnetized in the diameter direction. The magnetizeddirection is changed alternately at an equal interval in thecircumferential direction. Thus, the S pole and the N pole are arrangedon an outer peripheral surface of the encoder 108 alternately at anequal interval in the circumferential direction.

Then, an insertion hole 109 is formed in the middle portion of the outerring 6 in the axial direction, which is located in a discontinuousportion of the stationary flange 12 in the circumferential direction, ina state that such insertion hole passes through the outer ring 6 fromthe outer peripheral surface to the inner peripheral surface in theradial direction. A rotation speed sensor (not shown) can be insertedinto the inner side of this insertion hole 109. In operation of thewheel bearing unit, the rotation speed sensor is inserted into thisinsertion hole 109 and fixed thereto in such a manner that a sensingportion provided to a top end surface of the rotation speed sensor ispositioned to oppose to the outer peripheral surface of the encoder 108via a small clearance. Here, preferably the insertion hole 109 should beformed in the neighborhood of the horizontal area of the outer ring 6 isa fitted state of the wheel bearing unit to a suspension. The reason forthis is that, if the insertion hole 109 is formed in the area to whichthe load is most hard to be applied, the influence of formation of theinsertion hole 109 on a strength reduction of the outer ring 6 can besuppressed to the lowest minimum. Also, out of opening portions on bothends of the insertion hole 109, an opening portion formed on the innerperipheral surface side of the outer ring 6 is opposed to a sensedportion of the encoder 108, i.e., the outer peripheral surface of theencoder 108. Also, out of the opening portions on both ends of theinsertion hole 109, a stop plug 110 is detachably attached to theopening portion formed on the outer peripheral surface side of the outerring 6.

This stop plug 110 is integrally formed of the elastic material such asthe elastomer like a synthetic rubber, a vinyl, etc., a synthetic resin,or the like, and has a fitting portion 111, a stopper portion 112, and aknob portion 113. The fitting portion 111 is formed like a bottomedcircular cylinder consisting of a cylinder portion 114 and a bottomplate portion 115. Because an outer diameter of the cylinder portion 114in its free condition is formed slightly larger than an inner diameterof the insertion hole 109, the fitting portion 111 can be fitted intothe insertion hole 109 by means of the interference fit. Also, thebottom plate portion 115 stops one end of the cylinder portion 114 (anend portion on the inner diameter side of the outer ring 6 in a statethat the stop plug is fitted into the outer ring 6 i.e., an upper endportion in FIGS. 5 to 7). Also, the stopper portion 112 is formed on theother end of the cylinder portion 114 (an end portion on the outerdiameter side of the outer ring 6 in a state that the stop plug isfitted into the outer ring 6, i.e., a lower end portion in FIGS. 5 to 7)like an outward-directed flange. The stopper portion 112 is shaped tofit in with the outer peripheral surface of the outer ring 6. In thiscase, the stopper portion 112 has an outer diameter that is sufficientlylarger than an outer diameter of a chamfered portion 116 (FIG. 6) thatis formed on the opening end portion on the outer diameter side of theinsertion hole 109. Also, the knob portion 113 is arranged on the innerside of the cylinder portion 114, and its base end portion (an upper endportion in FIGS. 5 to 7) is coupled to the bottom plate portion 115 andits top end portion (a lower end portion in FIGS. 5 to 7) is protrudedfrom the opening on the other end of the cylinder portion 114 such thatthe knob portion can be pinched by the fingers or the tool such as thepliers, or the like.

In the case where the stopper portion 112 is curved along the outerperipheral surface of the outer ring 6, such stopper portion 112 canfulfill satisfactorily a role that stops the opening on the end portionof the insertion hole 109. Therefore, the outer peripheral shape of thefitting portion 111 is not always shaped into a cylindrical shape. Forexample, this outer peripheral shape may be shaped into a polygonalshape such as a triangle whose corners are rounded (triangular rice ballshape), a quadrangle, a hexagon, or the like. Conversely, if the fittingportion 111 is shaped into a circular cylinder and then the insertionhole 109 is stopped by this fitting portion 111, the presence of aclearance between the stopper portion 112 and the outer peripheralsurface of the outer ring 6 may be allowed in a situation that thestopper portion 112 is shaped into a flat plate and then the stop plug110 is fitted into the opening portion on the end portion of theinsertion hole 109. Such clearance can give a clue to the tool such as astandard screwdriver, or the like used when the stop plug 110 is takenout from the insertion hole 109. Therefore, in case the stopper portion112 is shaped to give the above clearance, the knob portion 113 can beomitted. Also, there is no necessity for providing the interference tothe full length of the outer peripheral surface of the fitting portion111 in the axial direction, and a shape that provides the interferenceonly to a part of the full length in the axial direction may beemployed. Also, a flat portion may be formed on the outer peripheralsurface of the outer ring 6 in the peripheral area of the openingportion of the insertion hole 109. In the case where the flat portion isformed like the above, the side surface of the fitting flange can bebrought into tight contact with the flat portion even though such sidesurface of the fitting flange provided to the base end portion of therotation speed sensor is formed as a simple flat surface. Also, in thecase where the flat portion is formed like the above, the stopperportion 112 can also be brought into tight contact with the flat portionif such stopper portion 112 provided to the stopper portion 112 isformed like a flat plate, so that the end portion of the opening portionof the insertion hole 109 can be closed by the stopper portion 112.

Also, in the case of the present embodiment, the turning process isapplied to the outer side surface of the rotary flange 13 provided tothe outer peripheral surface of the hub 8 in a predetermined position,and thus such outer side surface is finished into predetermined shapeand dimension. In other words, in the case where the turning process isapplied to the outer side surface, first respective constituent membersof the wheel bearing unit are assembled into a state shown in FIG. 5.That is, the outer ring 6, the hub 8, the inner ring 16, and a pluralityof balls 17, 17 are assembled under the condition that a plurality ofballs 17, 17 are provided between the outer ring raceways 11 a, 11 bprovided on the inner peripheral surface of the outer ring 6 and theinner ring raceways 14 a, 14 b provided to the outer peripheral surfacesof the hub 8 and the inner ring 16 respectively. Also, a pair of sealrings 19 a, 19 b are provided between the inner peripheral surface ofthe outer ring 6 on both end sides and the outer peripheral surfaces ofthe hub 8 and the inner ring 16 respectively, and the encoder 108 isprovided to the outer peripheral surface of the hub 8. Further, the stopplug 110 is fitted/fixed into the insertion hole 109 provided in theouter ring 6. In this condition, the internal space in which the encoder108 is provided is isolated from the outside and is sealed tightly.

In this situation, the wheel bearing unit 5 the outer side surface ofthe rotary flange 13 of which is subjected to the turning process isfitted to a turning machine 38 a. In this case, a portion of the outerperipheral surface of the outer ring 6, which is deviated toward theinner end side rather than the inner side surface of the stationaryflange 12, is clamped by the top end portions of the chuck 39constituting the turning machine 38 a. Then, a top end portion of arotating shaft 40 a of the turning machine 38 a is inserted into thespline hole 20 provided at the center portion of the hub 8, and thus aportion of the top end portion, on an outer peripheral surface of whicha male spline portion is formed, is engaged with a female spline portion53 formed on the inner peripheral surface of the spline hole 20. Then,the rotating shaft 40 a is rotated/driven under the above condition toturn the hub 8 on its central axis, and then the turning process isapplied to the outer side surface of the rotary flange 13 by putting aprecision machining tool (not shown) to such outer side surface, andthus the outer side surface of the rotary flange is finished intopredetermined shape and dimension. Thus, the wheel bearing unit 5 iscompleted. Then, the stop plug 110 is removed from the insertion hole109 provided in the outer ring 6 after the turning process is applied tothe outer side surface of the rotary flange 13 but before the outer ring6 is coupled/fixed to the knuckle 3 (see FIG. 21). This removingoperation is executed by pinching the top end portion of the knobportion 113 by the fingers or the tool, or the like and then pulling outthe knob portion 113 outward (downward in FIGS. 1 to 3) in the diameterdirection of the outer ring 6. When the knob portion 113 is pulled outin this manner, the bottom plate portion 115 and the cylinder portion114 are elastically deformed as indicated by a chain line in FIG. 7, andthus a contact pressure between the outer peripheral surface of thecylinder portion 114 and the inner peripheral surface of the insertionhole 109 is reduced. As a result, the stop plug 110 can be pulled outfrom the insertion hole 109 by a relatively small force.

In the case of the present embodiment constructed as above, since thestop plug 110 is inserted/fixed into the insertion hole 109 provided inthe outer ring 6 while the turning process is applied to the outer sidesurface of the rotary flange 13, the internal space 26 in which theencoder 108 is provided is isolated from the outside and is tightlysealed. Therefore, when the outer side surface of the rotary flange 13is processed into the predetermined shape and dimension, the adhesion ofthe chips generated in this process on the outer peripheral surface ofthe encoder 108 through the insertion hole 109 can be prevented. As aresult, a sensing performance of the rotation speed sensor that ispositioned to oppose to the outer peripheral surface of the encoder 108can be satisfactorily assured.

Since other structures and operations are similar to those in the aboveconventional configuration shown in FIG. 21 and in the foregoing firstembodiment, their redundant explanation will be omitted herein byaffixing the same reference numerals to like portions respectively. Inthe case of the present embodiment, unlike the above first embodiment, afitting hole 25 through which the base end portion of the stud 9 (seeFIG. 21) is press-fitted/fixed is formed at plural locations of therotary flange 13 in the circumferential direction. An inner peripheralsurface of these fitting holes 25 is formed as a plain cylindricalsurface on which the internal thread portion is not provided. In thecase of such present embodiment, the turning process is applied to theouter side surface of the rotary flange 13 after the base end portionsof the studs 9 are press-fitted/fixed into these fitting holes 25. Also,an annular groove (not shown) having a center of rotation of the rotaryflange 13 as its center is formed in a portion of the outer side surfaceof the rotary flange 13, which contains the opening ends of the fittingholes 25, before the turning process is applied to the outer sidesurface. The turning process cannot be applied to peripheral portions ofthese studs 9 and portions located between the neighboring studs 9 inthe circumferential direction, nevertheless such an event can beprevented owing to the presence of the above annular groove that, whenthe turning process is applied to the outer side surface of the rotaryflange 13, above portions out of the outer side surface are protruded inthe axial direction from the remaining portion that has been subjectedto the turning process.

Next, FIGS. 8 and 9 show a third embodiment of the present invention,which also corresponds to claims 1, 3, 4, and 6. In the case of thepresent embodiment, unlike the case of the second embodiment shown inabove FIGS. 5 to 7, the inner end surface of the inner ring 16 that isfitted onto the inner end portion of a hub 8 b is held by the caulkedportion 24 that is formed by plastically deforming the cylinder portion71, which is provided to the inner end portion of the hub 8 b, outwardin the diameter direction by means of the caulking. Also, in the case ofthe present embodiment, unlike the case of the second embodiment shownin above FIGS. 5 to 7, the encoder is not fitted onto the outerperipheral surface of the hub 8 b. Also, the insertion hole, whichpasses through in the diameter direction and through which the rotationspeed sensor can be inserted, is not formed in the middle portion of theouter ring 6 in the axial direction. Alternately, in the case of thepresent embodiment, an encoder 28 is fixed to a part of the seal ring 19b that is provided between the inner peripheral surface of the inner endportion of the outer ring 6 and the outer peripheral surface of theinner end portion of the inner ring 16. In other words, this seal ring19 b consists of a slinger 27 that is formed as an annular ring as awhole to have an L-shaped cross section and fitted/fixed onto the innerend portion of the inner ring 16, a reinforcing member 42 that is formedas an annular ring as a whole to have an L-shaped cross section andfitted/fixed into the inner end portion of the outer ring 6, and anelastic member 43 a base end portion of which is coupled/fixed to thereinforcing member 42. Also, a top end edge of the seal lip constitutingthe elastic member 43 is brought into contact with the outer peripheralsurface and the outer side surface of the slinger 27 to slide thereon.

Also, the encoder 28 is fixed to the inner surface of the slinger 27.This encoder 28 is made of a rubber magnet on which the S pole and the Npole are arranged alternately in the circumferential direction. Moreparticularly, the encoder 28 is the circular-ring rubber magnet that isformed by mixing the ferrite powders into the rubber, and is magnetizedin the axial direction. The magnetized direction is changed alternatelyat an equal interval in the circumferential direction. Therefore, the Spole and the N pole are arranged alternately at an equal interval on theinner surface of the encoder 28 in the circumferential direction. Inoperation of the wheel bearing unit 5, the sensing portion of therotation speed sensor (not shown) secured to the outer ring 6, theknuckle 3 (see FIG. 21), or the like is opposed to the inner surface asthe sensed portion of the encoder 28 via a small clearance. Then, anoutput signal of the rotation speed sensor, which is changed in responseto the rotation speed of the encoder 28, can be picked up. The encoder28 and the rotation speed sensor constitutes the rotation speed sensingdevice that can sense the rotation speed of the wheel fixed to the hub 8b.

Also, in the case of the present embodiment, the outer side surface ofthe rotary flange 13 provided to the outer peripheral surface of the hub8 b is finished into the predetermined shape and dimension by applyingthe turning process in a predetermined position. More specifically, inthe case where the turning process is applied to the outer side surface,respective constituent members of the wheel bearing unit 5 are assembledinto a state shown in FIG. 8 and also a cover 30 is fitted/fixed intothe portion that is located near the inner end of the inner peripheralsurface of the spline hole 20, which is provided at the center portionof the hub 8 b, and gets out of the area in which the female splineportion 53 is formed. This cover 30 is made of a synthetic resin such aspolyethylene terephthalate (PET), or the like by using the injectionmolding, or the like. The cover 30 has a fitted cylinder portion 50formed like a bottomed circular cylinder, and a pressing collar portion51 provided to the middle portion of the outer peripheral surface of thefitted cylinder portion 50 and formed like an outward-directed flange.In the fitted cylinder portion 50, a small-diameter cylinder portion 117and a large-diameter cylinder portion 118 are concentrically coupled viaa stepped portion 119 and also the outer end portion of thesmall-diameter cylinder portion 117 is stopped by a bottom plate portion120. Also, plural locations (eight locations in the illustrated case) ofthe small-diameter cylinder portion 117 in the circumferential directionare expanded toward the outer diameter side over an almost full lengthalong the axial direction, and thus projected portions 52, 52 projectedon the outer diameter side are provided to that portions. In the case ofthe present embodiment, a thickness t₁₁₇ of the small-diameter cylinderportion 117 including the projected portions 52, 52 is set to the samedimension as a whole. Also, a diameter of a circumscribed circle ofthese projected portions 52, 52 in their free state is set slightlylarger than an inner diameter of a portion of the inner end portion ofthe spline hole 20, which is deviated from the area in which the femalespline portion 53 is formed. In addition, a portion of the pressingcollar portion 51 positioned near the outer diameter is formed as ataper portion 121 whose diameter is increased gradually toward its topend edge.

In applying the turning process to the outer side surface of the rotaryflange 13, first respective constituent members of the wheel bearingunit 5 are assembled and also the fitted cylinder portion 50 of thecover 30 is fitted/fixed into the inner end portion of the spline hole20 provided in the hub 8 b via plural projected portions 52, 52 by meansof a small interference fit. Thus, the space in which the encoder 28 isprovided is isolated from the outside and is sealed tightly. Also, theouter side surface of the portion of the pressing collar portion 51located near the inner diameter is pressed against the inner sidesurface of the caulked portion 24 provided to the inner end portion ofthe hub 8 b, and also the top end edge of the taper portion 121positioned near the outer diameter of the pressing collar portion 51 ispressed against the inner end surface of the outer ring 6. Under thiscondition, the wheel bearing unit 5 to the outer side surface of therotary flange 13 of which the turning process is applied is fitted tothe turning machine 38 a (see FIG. 5). Also, the top end portion of therotating shaft 40 a (see FIG. 5) of the turning machine 38 a is insertedinto the inside of the spline hole 20 from the outside in the axialdirection, and then is spline-engaged with the female spline portion 53of the spline hole 20. In this situation, the turning process is appliedto the outer side surface of the rotary flange 13 while rotating/drivingthe rotating shaft 40 a. The cover 30 is removed from the inner endportion of the hub 8 b after this turning process but before the outerring 6 is coupled/fixed to the knuckle 3 (see FIG. 21).

As described above, in the case of the present embodiment, a spacebetween the inner peripheral surface of the inner end portion of theouter ring 6 and the outer peripheral surface of the inner end portionof the hub 8 b are isolated mutually and sealed tightly with the cover30 while the turning process is applied to the outer side surface of therotary flange 13. Therefore, it can be prevented that the chipsgenerated in applying the turning process to the outer side surface ofthe rotary flange 13 adhere to the outer side surface of the encoder 28.Also, because the operator can grasp the large-diameter cylinder portion118 that is projected from the inner end surface of the hub 8 b in thebase half portion (the right half portion in FIG. 8) of the fittedcylinder portion 50 constituting the cover 30, an operation of removingthe cover 30 from the hub 8 b is easily done by such operator before thewheel bearing unit 5 is fitted to the suspension system.

Also, in the case of the present embodiment, the fitted cylinder portion50 of the cover 30 is fitted/fixed into the inner end portion of thespline hole 20 via a plurality of projected portions 52, 52 during theturning process applied to the outer side surface of the rotary flange13. For this reason, a dimensional tolerance of the inner diameter ofthe inner end portion of the spline hole 20 can be set large like about0.2 mm, and also the fitted cylinder portion 50 can be detachablyattached easily to the spline hole 20 by a small force even when theinner diameter of the inner end portion of the spline hole 20 isprocessed smaller than a normal dimension.

Since other structures and operations are similar to those in the secondembodiment shown in above FIGS. 5 to 7, their redundant explanation willbe omitted herein by affixing the same reference numerals to likeportions respectively.

Next, FIG. 10 shows a fourth embodiment of the present invention, whichalso corresponds to claims 1, 3, 4, and 6. In the case of the presentembodiment, unlike the third embodiment shown in above FIGS. 8 and 9, apair of inner rings 16 a, 16 b are fitted/fixed onto the middle portionand the inner end portion of the outer peripheral surface of the hub 8 bin the axial direction respectively. Also, the inner ring raceways 14 a,14 b are formed on outer peripheral surfaces of these inner rings 16 a,16 b respectively. Also, a pair of seal rings 19 a, 19 b for sealingtightly the internal space 26 in which a plurality of balls 17, 17 areprovided are provided between the outer peripheral surfaces of the endportions of the inner rings 16 a, 16 b and the inner peripheral surfacesof both end portions of the outer ring 6.

Also, the turning process is applied to the outer side surface of therotary flange 13 provided to the outer peripheral surface of the hub 8 bin a predetermined position, and thus such outer side surface isfinished to the predetermined shape and dimension. When the turningprocess is applied to the outer side surface, respective constituentmembers of the wheel bearing unit 5 are assembled in the state shown inFIG. 10 in the parts maker that manufactures the wheel bearing unit 5. Acover 30 a formed like a bottomed circular cylinder is fitted/fixed ontothe outer peripheral surface of the small-diameter stepped portion 29 ofthe outer ring 6 formed on the inner half portion that is deviatedinward rather than the inner side surface of the stationary flange 12 inthe axial direction. This cover 30 a is made of a synthetic resin suchas polyethylene terephthalate (PET), or the like by using the injectionmolding, or the like. The cover 30 a has a cylinder portion 31, and abottom plate portion 32 that closes the inner end of the cylinderportion 31. Also, plural locations (e.g., ten locations) of the cylinderportion 31 in the circumferential direction are expanded toward theinner diameter side over an almost full length along the axialdirection, and thus projected portions 125, 125 projected on the innerdiameter side are provided at plural locations of the inner peripheralsurface of the cylinder portion 31 in the circumferential direction.Also, a diameter of an inscribed circle of these projected portions 125,125 in their free state is set slightly smaller than an outer diameterof the small-diameter stepped portion 29 provided to the inner endportion of the outer ring 6. Also, a thickness t_(30a) of the cover 30 ais set to the same dimension as a whole. Then, dimensions of respectiveportions are regulated such that the thickness t_(30a) of the cover 30a, a diameter d₂₉ of the small-diameter stepped portion 29, and adiameter d₃₆ of the large-diameter circular cylinder portion 36 providedto the outer peripheral surface of the outer ring 6 between the innerside surface of the stationary flange 12 and the small-diameter steppedportion 29 can satisfy a relationship of d₃₆>d₂₉+2t_(30a).

In applying the turning process to the outer side surface of the rotaryflange 13, first respective constituent members of the wheel bearingunit 5 are assembled into a state shown in FIG. 10 and also the cylinderportion 31 of the cover 30 a is fitted/fixed onto the small-diameterstepped portion 29 provided to the inner end portion of the outer ring 6via plural projected portions 125, 125 by means of a small interferencefit. In this condition, the space in which the encoder 28 is provided isisolated from the outside and sealed tightly. Also, the outer sidesurface of the bottom plate portion 32 constituting the cover 30 a ispushed against the end surface of the caulked portion 24 that isprovided to the inner end portion of the hub 8 b. Then, the wheelbearing unit 5 is fitted to the turning machine 38 a (see FIG. 5) inthis situation. In other words, the large-diameter circular cylinderportion 36 provided on the portion of the outer peripheral surface nearthe inner end of the outer ring 6 is grasped by the chuck 39 (see FIG.5) of the turning machine 38 a. In the case of the illustrated example,a diameter d₃₁ of a circumscribed circle of the cylinder portion 31constituting the cover 30 a is set larger than a diameter d₃₆ of thelarge-diameter circular cylinder portion 36 (d₃₁>d₃₆) in a stateobtained before the large-diameter circular cylinder portion 36 isgrasped by the chuck 39. In this case, since the thickness t_(30a) ofthe cover 30 a, the diameter d₃₆ of the large-diameter circular cylinderportion 36, and the diameter d₂₉ of the small-diameter stepped portion29 satisfy the above relationship (d₃₆>d₂₉+2t_(30a)), a diameter ofportions, which are displaced from the projected portions 125, 125 inthe circumferential direction, of the cylinder portion 31 of the cover30 a is elastically reduced by the top end portions of the chuck 39 whenthe large-diameter circular cylinder portion 36 is grasped by the abovetop end portions from the outer diameter side. Then, the outerperipheral surface of the cylinder portion 31 is never protruded towardthe outer diameter side beyond the large-diameter circular cylinderportion 36. As a result, the cover 30 a never offers an obstruction whenthe chuck 39 clamps the large-diameter circular cylinder portion 36.

Then, the top end portion of the rotating shaft 40 a (see FIG. 5) of theturning machine 38 a is inserted into the inside of the spline hole 20from the outside in the axial direction, and then is spline-engaged withthe female spline portion 53 of the spline hole 20. In this situation,the turning process is applied to the outer side surface of the rotaryflange 13 while rotating/driving the rotating shaft 40 a. The cover 30 ais removed from the inner end portion of the outer ring 6 after thisturning process but before the outer ring 6 is coupled/fixed to theknuckle 3 (see FIG. 21).

As described above, in the case of the present embodiment, such an eventcan also be prevented that the chips generated in applying the turningprocess to the outer side surface of the rotary flange 13 adhere to theouter side surface of the encoder 28.

Since other structures and operations are similar to those in the thirdembodiment shown in above FIGS. 8 and 9, their redundant explanationwill be omitted herein by affixing the same reference numerals to likeportions respectively.

Next, FIG. 11 shows a fifth embodiment of the present invention, whichalso corresponds to claims 1, 3, 4, and 6. In the case of the presentembodiment, in applying the turning process to the outer side surface ofthe rotary flange 13 provided to the outer peripheral surface of the hub8 b, a cover 30 b shaped into an annular ring is fitted/fixed onto thesmall-diameter stepped portion 29 provided to the outer peripheralsurface of the inner end portion of the outer ring 6. In other words,the cover 30 b is formed like the annular ring that has a circular ringportion 46, and a cylinder portion 47 extended from the outer peripheraledge of this circular ring portion 46 in the axial direction. Also, aninner peripheral edge of the circular ring portion 46 is formed as ataper portion 123 that is inclined over a full circumference tosubstantially fit in with a profile of the inner peripheral edge portionof the caulked portion 24 that is provided to the inner end portion ofthe hub 8 b.

In applying the turning process to the outer side surface of the rotaryflange 13, first respective constituent members of the wheel bearingunit 5 are assembled and also the cylinder portion 47 of the cover 30 bis fitted/fixed onto the small-diameter stepped portion 29 provided tothe outer peripheral surface of the inner end portion of the outer ring6 by means of a small interference fit. Also, an outer side surface ofthe taper portion 123 provided to the inner peripheral edge portion ofthe cover 30 b is thrust against the inner side surface of the caulkedportion 24. In this condition, the space in which the encoder 28 isprovided is isolated from the outside and is sealed tightly. In thissituation, the wheel bearing unit 5 to the outer side surface of therotary flange 13 of which the turning process is applied is fitted to aturning machine 38 b. In this case, the large-diameter circular cylinderportion 36 provided on the portion of the outer peripheral surface nearthe inner end of the outer ring 6 is clamped by the chuck 39. Also, thetop end portion of the rotating shaft 40 a of the turning machine 38 bis inserted into the inside of the spline hole 20 provided to the hub 8b from the outside in the axial direction, and then is spline-engagedwith the female spline portion 53 of the spline hole 20. Then, underthis condition, the outer side surface of the rotary flange 13 isfinished into the predetermined shape and dimension by putting theprecision machining tool 104 to this outer side surface whilerotating/driving the rotating shaft 40 a.

In the case of the present embodiment, the chips generated in theturning process applied to the outer side surface of the rotary flange13 can be prevented from adhering on the inner side surface of theencoder 28.

Since other structures and operations are similar to those in the fourthembodiment shown in above FIG. 10, their redundant explanation will beomitted herein by affixing the same reference numerals to like portionsrespectively. In the case of the present embodiment, the rotating shaft40 a of the turning machine 38 b is arranged on the inner diameter sideof the chuck 39.

Next, FIG. 12 shows a sixth embodiment of the present invention, whichalso corresponds to claims 1, 3, 4, and 6. In the case of the presentembodiment, in the configuration in the fourth embodiment shown in aboveFIG. 10, the outer peripheral surface of an outer ring 6 a is formed asa simple circular cylindrical surface to which the stationary flange isnot provided. In this configuration of the present embodiment, when theturning process is applied to the outer side surface of the rotaryflange 13 provided to the outer peripheral surface of the hub 8 b, themiddle portion of the outer peripheral surface of the outer ring 6 a,which is deviated from the portion onto which the cover 30 a isfitted/fixed, in the axial direction is grasped by the chuck 39 of theturning machine 38 a. Also, the top end portion of the rotating shaft 40a of the turning machine 38 a is inserted into the inside of the splinehole 20 provided to the hub 8 b from the outside in the axial direction,and then is spline-engaged with the female spline portion 53 of thespline hole 20. Then, under this condition, the outer side surface ofthe rotary flange 13 is finished into the predetermined shape anddimension by putting the precision machining tool 104 to this outer sidesurface while rotating/ driving the rotating shaft 40 a.

Since other structures and operations are similar to those in the fourthembodiment shown in above FIG. 10, their redundant explanation will beomitted herein by affixing the same reference numerals to like portionsrespectively.

Next, FIGS. 13 and 14 show a seventh embodiment of the presentinvention, which corresponds to claims 2, 3, 5, and 6. In a wheelbearing unit of the present embodiment, in the wheel bearing unit of thethird embodiment shown in above FIGS. 8 and 9, the rotor 2 (FIG. 14) asthe braking rotating body is coupled/fixed to the outer side surface ofthe rotary flange 13 provided to the outer peripheral surface of the hub8 b. Also, in the wheel bearing units of the above embodiments, theouter side surface of the rotary flange 13 is finished into thepredetermined shape and dimension by applying the turning process tothis outer side surface in the predetermined position. In contrast, inthe case of the wheel bearing unit of the present embodiment, theturning process is not applied to the outer side surface of the rotaryflange 13 in such state. Alternately, in the case of the presentembodiment, the turning process is applied to both side surfaces, whichare located near the outer diameter and serve as the braking frictionsurface respectively, of the rotor 2, which is coupled/fixed to theouter side surface of the rotary flange 13, in the predeterminedcondition. Also, in the case of the present embodiment, thesmall-diameter stepped portion 29 is formed on the inner half portion,which is shifted toward the inner end side from the inner side surfaceof the stationary flange 12, of the outer peripheral surface of theouter ring 6. Also, the base end portion of the stud 9 ispress-fitted/fixed to the inside of the fitting holes 25, which areprovided to plural locations in the circumferential direction of therotary flange 13, respectively.

In order to couple/fix the rotor 2 to the outer side surface of therotary flange 13, in the case of the present embodiment, a threaded hole33 is formed in two positions in the circumferential direction of therotary flange 13. Also, through holes 34 (FIG. 14) are formed inpositions that are located near the inner diameter of the rotor 2 andlocated in alignment with the threaded holes 33 respectively. Then, asshown in FIG. 14, tentatively setting screws 35 are passed through thethrough holes 34 and then screwed tightly into the threaded holes 33 ina state that the inner side surface of the rotor 2 near the innerdiameter is put on the outer side surface of the rotary flange 13. Withthis arrangement, the rotor 2 is coupled/fixed to the outer side surfaceof the rotary flange 13. The rotor 2 is shaped into the rough profile bythe casting, or the like, and then the inner side surface that comes intouch with the rotary flange 13 is finished smoothly by applying amachining process to the inner side surface before the rotor 2 iscoupled/fixed to the rotary flange 13. Therefore, the rotor 2 can becoupled/fixed to the outer side surface of the rotary flange 13 withoutplay. Then, portions of both side surfaces of the rotor 2 near the outerdiameter are finished into predetermined shape and dimension by applyingthe turning process to both side surfaces in a predetermined position.

More particularly, when the turning process is applied to the portionsof both side surfaces of the rotor 2 near the outer diameter, firstrespective parts of respective constituent members of the wheel bearingunit 5 are processed into the predetermined shape and dimension in theparts maker that manufactures the wheel bearing unit 5. Then, respectiveconstituent members of the wheel bearing unit 5 are assembled into astate shown in FIG. 13 in the parts maker that manufactures the wheelbearing unit 5 before the rotor 2 is coupled. In other words, the outerring 6, the hub 8 b, the inner ring 16, and a plurality of balls 17, 17are assembled together in a condition that a plurality of balls 17, 17are provided between the outer ring raceways 11 a, 11 b provided on theinner peripheral surface of the outer ring 6 and the inner ring raceways14 a, 14 b provided on the outer peripheral surfaces of the hub 8 b andthe inner ring 16 respectively. Then, a pair of seal rings 19 a, 19 bare provided between the inner peripheral surface of the both endportions of the outer ring 6 and the outer peripheral surfaces of thehub 8 a and the end portion of the inner ring 16. Then, the base endportions of a plurality of studs 9 are fixed to the rotary flange 13.

Then, a cover 30 c is fitted/fixed onto the small-diameter steppedportion 29 provided to the outer peripheral surface of the inner endportion of the outer ring 6. This cover 30 c is formed into a bottomedcircular cylinder that has the cylinder portion 31 and the bottom plateportion 32 that stops the inner end of the cylinder portion 31, byinjection-molding an inexpensive synthetic resin such as polypropylene(PP), polyethylene (PE), or the like. The cover 30 c is fitted to theinner end portion of the outer ring 6 by fitting/fixing the cylinderportion 31 onto the small-diameter stepped portion 29 by means of theclearance fit or the small interference fit. Also, the top end portionof the cylinder portion 31 of the cover 30 c is pushed to abut againstthe large-diameter circular cylinder portion 36, which is provided on aportion of the outer peripheral surface of the outer ring 6 between theinner side surface of the stationary flange 12 and the small-diameterstepped portion 29, and a stepped surface 37 formed as a discontinuousportion between the small-diameter stepped portion 29 and thelarge-diameter circular cylinder portion 36 on the outer peripheralsurface of the inner end portion of the outer ring 6. With thisarrangement, the space in which the encoder 28 is provided is isolatedfrom the outside of the cover 30 c and sealed tightly. This cover 30 ccan be detachably attached easily to the small-diameter stepped portion29 by a small force (of 20 N or less). In the case where the cover 30 ccan be detachably attached easily to the small-diameter stepped portion29 in this manner, the cover 30 c is liable to come off from the innerend portion of the outer ring 6 when the wheel bearing unit 5 to whichthe cover 30 c is fitted is carried while directing this cover 30 cdownward. In order to prevent such disengagement, this cover 30 c ispositioned upward while the wheel bearing unit 5 to which the cover 30 cis fitted is carried. In the case of the present embodiment, dimensionsof respective portions are regulated such that an outer diameter of thecover 30 c is set slightly smaller than an outer diameter of thelarge-diameter circular cylinder portion 36 in a condition that thecover 30 c is fitted/fixed onto the small-diameter stepped portion 29.

Such wheel bearing unit 5 prior to a state that the rotor 2 is coupledthereto is carried from the parts maker to the assembling maker thatmanufactures a finished product of the wheel bearing unit 5. Then, inthe assembling maker, the portion near the inner diameter of the rotor 2that is carried from another parts maker is coupled/fixed to the outerside surface of the rotary flange 13 provided to the hub 8 b by thetentatively setting screws 35. Then, as shown in FIG. 14, the wheelbearing unit 5 to both side surfaces of the rotor 2 of which the turningprocess is applied is fitted to the turning machine 38 a in thiscondition. In this event, the large-diameter circular cylinder portion36 provided to the portion of the outer ring 6 near the inner end isclamped by the top end portions of the chuck 39 constituting the turningmachine 38 a. Also, the top end portions of the chuck 39 are thrustagainst the inner side surface of the stationary flange 12.

Then, the top end portion of the rotating shaft 40 a of the turningmachine 38 a is inserted into the inside of the spline hole 20 providedat the center portion of the hub 8 b from the outside in the axialdirection, and then is spline-engaged with the female spline portion 53provided to the inner peripheral surface of the spline hole 20. In thissituation, the turning process is applied to both side surfaces of therotor 2 near the outer diameter by putting two precision machining tools41 a, 41 b to these portions while rotating/driving the hub 8 b on itscentral axis by rotating/driving the rotating shaft 40 a. Thus, bothside surfaces of the rotor 2 are finished into the predetermined shapeand dimension. In this case, the precision machining tools 41 a, 41 bapply the turning process to both side surfaces while moving on a planethat intersects orthogonally with a center-of-rotation axis of the hub 8b respectively. At the same time, the outer peripheral surface of therotor 2 is finished into the predetermined shape and dimension byputting another precision machining tool 41 c to such outer peripheralsurface, whereby the wheel bearing unit 5 is finished to a finishedproduct. The cover 30 c is removed from the inner end portion of theouter ring 6 after the turning process is applied to both side surfacesof the rotor 2 but before the outer ring 6 is coupled/fixed to theknuckle 3 (see FIG. 21). In this fashion, unlike the cover 74 used inthe first embodiment shown in above FIGS. 1 to 4, for example, the coveras the constituent element of the present invention is different fromthe cover that is fitted to the inner end portion of the outer ring 6 ora rotating member 23 b as it is in a condition that the wheel bearingunit is fitted to the suspension system, and does not support therotation speed sensor.

As described above, in a method of manufacturing the wheel bearing unitand the wheel bearing unit obtained by this manufacturing methodaccording to the present embodiment, both side surfaces of the rotor 2near the outer diameter are finished into the predetermined shape anddimension by applying the turning process to both side surfaces of therotor 2 while rotating the rotating member 23 b to which the rotor 2 iscoupled/fixed around the outer ring 6 in a state that respectiveconstituent members of the wheel bearing unit 5 are assembled. For thisreason, in the case of the present invention, when both side surfaces ofthe rotor 2 near the outer diameter, which serve as the braking frictionsurface respectively, are finished into the predetermined shape anddimension, such an event can be eliminated that a dimensional error oran assembling error that is inevitable in manufacturing a plurality ofparts existing between the knuckle 3 and the rotor 2 leads to theworsening of a perpendicularity of both side surfaces to a center ofrotation of the rotating member 23 b. Therefore, the swing of both sidesurfaces can be suppressed smaller than that in above embodiments andsufficiently. Also, since there is no necessity to improve particularlya dimensional accuracy of a plurality of parts existing between theknuckle 3 and the rotor 2, a cost required to suppress the swing of bothside surfaces can be suppressed sufficiently.

Further, in the case of the present embodiment, while the turningprocess is applied to both side surfaces of the rotor 2, the space inwhich the encoder 28 is provided is isolated from the outside of thecover 30 c by fitting/fixing the cover 30 c onto the inner end portionof the outer ring 6. Therefore, when both side surfaces of the rotor 2are to be processed into the predetermined shape and dimension, theadhesion of the chips generated in this processing onto the inner sidesurface of the encoder 28 can be prevented. As a result, a sensingperformance of the rotation speed sensor that is opposed to the innerside surface of the encoder 28 can be assured sufficiently. Also, in thecase of the present embodiment, the particular consideration to preventthe adhesion of the chips onto the inner side surface of the encoder 28is not required of the assembling maker that applies the turning processto both side surface of the rotor 2. In addition, in the case of thepresent embodiment, the bottomed circular cylinder-like cover 30 chaving the bottom plate portion 32 in which the through hole to passthrough both side surfaces is not provided is fitted/fixed onto theinner end portion of the outer ring 6, and also the turning process isapplied to both side surfaces of the rotor 2 in a condition that the topend portion of the rotating shaft 40 a of the turning machine 38 a isinserted into the inside of the spline hole 20 provided to the hub 8 bfrom the outside in the axial direction. As a result, in the case of thepresent embodiment, it can be prevented more effectively that the chipsgenerated in the turning process enters into the space in which theencoder 28 is provided.

Also, according to the present embodiment, while the wheel bearing unit5 manufactured by the parts maker prior to the coupling of the rotor 2is carried to the assembling maker that manufactures a finished productof the wheel bearing unit 5, and so forth after the outer ring 6, therotating member 23 b, and a plurality of balls 17, 17 are assembled andalso the cover 30 c is fitted/fixed onto the inner end portion of theouter ring 6, adhesion of the foreign matter such as the magnetic power,or the like onto the inner side surface of the encoder 28 can beprevented until portions of both side surfaces of the rotor 2 near theouter diameter have been processed. In addition, if the cover 30 c isremoved from the inner end portion of the outer ring 6 immediatelybefore the outer ring 6 is coupled/fixed to the knuckle 3, adhesion ofthe foreign matter onto the inner side surface of the encoder 28 canalso be prevented after the fitting of the cover 30 c just before theabove removal while the wheel bearing unit 5 is carried from the partsmaker to the assembling maker, and so forth. Further, since the cover 30c is removed from the inner end portion of the outer ring 6 after theportions of both side surfaces of the rotor 2 near the outer diameterare processed but before the outer ring 6 is coupled/fixed to theknuckle 3, such cover 30 c never obstructs workings to combine therotation speed sensor with the wheel bearing unit 5, to fit the wheelbearing unit 5 to the car, and so on.

Also, in the case of the present embodiment, the large-diameter circularcylinder portion 36 provided to the outer peripheral surface near theinner end of the outer ring 6 is clamped by the chuck 39 constitutingthe turning machine 38 a. An improvement of the dimensional accuracy ofthe large-diameter circular cylinder portion 36 can be easily made.Therefore, the working of fitting the wheel bearing unit 5 to the sidesurface of the rotor 2 of which the turning process is applied to theturning machine 38 a can be easily done. In addition, in the case of thepresent embodiment, the turning process is also applied to the outerperipheral surface of the rotor 2 by putting the precision machiningtool 41 c to such outer peripheral surface in applying the turningprocess to both side surfaces of the rotor 2, and thus the outerperipheral surface is finished into the predetermined shape anddimension. The particularly high dimensional accuracy is not required ofthe outer peripheral surface of the rotor 2, but it is preferable thatthe turning process should be applied to ensure a high rotationalbalance. Because the turning process is applied to the outer peripheralsurface simultaneously with both side surfaces, a reduction in aproduction cost of the high-performance wheel bearing unit 5 can beattained.

Since other structures and operations are similar to those in the thirdembodiment shown in above FIGS. 8 and 9, their redundant explanationwill be omitted herein by affixing the same reference numerals to likeportions respectively.

Next, FIGS. 15 and 16 show an eighth embodiment of the presentinvention, which also corresponds to claims 2, 3, 5, and 6. In the caseof a wheel bearing unit of the present embodiment, unlike the case ofthe seventh embodiment shown in above FIGS. 13 and 14, the reinforcingmember 42 (see FIG. 13) to which the elastic member 43 is coupled is notfitted/fixed into the inner end portion of the outer ring 6. Therefore,no seal ring is present between the inner peripheral surface of theinner end portion of the outer ring 6 and the outer peripheral surfaceof the inner end portion of the inner ring 16.

Also, in the case of the present embodiment, out of a plurality of studs9 that are fixed to the rotary flange 13 provided to the hub 8 b, afitting portion 44 provided in an intermediate portion of any one stud 9is set larger in diameter than those of remaining suds. In conformitywith this, out of a plurality of through holes 45 that are provided tofit the fitting portions 44 of these studs 9 into portions of the rotor2 near the inner diameter (FIG. 16) without play, an inner diameter ofany one through hole 45 is set larger than those of remaining throughholes. As a consequence, only when the stud 9 having the large-diameterfitting portion 44 is inserted into the large-diameter through hole 45,the rotor 2 can be combined with the rotary flange 13 into a normalcondition, i.e., a condition that the inner side surface of the rotor 2near the inner diameter comes into contact with the outer side surfaceof the rotary flange 13. In the combined state in this manner, phases ofthe rotor 2 and the hub 8 b having the rotary flange 13 in thecircumferential direction are restricted uniquely.

Also, in the case of the present embodiment, in applying the turningprocess to both side surfaces of the rotor 2, a cover 30 d isfitted/fixed onto the small-diameter stepped portion 29 provided to theouter peripheral surface of the inner end portion of the outer ring 6.This cover 30 d is shaped into an annular ring that has the circularring portion 46, and the cylinder portion 47 extended from the outerperipheral edge of this circular ring portion 46 in the axial direction.Also, since an inner peripheral edge portion of the circular ringportion 46 is curved over a full circumstance along a shape of the innerperipheral edge portion of the caulked portion 24 provided to the innerend portion of the hub 8 b, such inner peripheral edge portion is shapedinto a curved portion 48.

In applying the turning process to both side surfaces of the rotor 2,first respective constituent members of the wheel bearing unit 5 areassembled prior to the fitting of the rotor 2, as shown in FIG. 15, andalso the cylinder portion 47 of the cover 30 d is fitted/fixed onto thesmall-diameter stepped portion 29 provided to the outer peripheralsurface of the inner end portion of the outer ring 6 by means of theclearance fit or the small interference fit. Also, an outer side surfaceof the curved portion 48 provided to the cover 30 d is pushed againstthe inner side surface of the caulked portion 24. Then, as shown in FIG.16, the fitting portions 44 provided to a plurality of studs 9 fixed tothe rotary flange 13 are mated in phase with a plurality of throughholes 45 provided to portions of the rotor 2 near the inner diameter,and then the inner side surface of the rotor 2 near the inner diameteris put on the outer side surface of the rotary flange 13 while fittingthese fitting portions 44 into these through holes 45 respectively.Then, the wheel bearing unit 5 to both side surfaces of the rotor 2 ofwhich the turning process is applied is fitted to the turning machine 38b in this condition. In this event, the large-diameter circular cylinderportion 36 provided to the outer peripheral surface near the inner endof the outer ring 6 is clamped by the chuck 39, and also a top endsurface of an annular piston 66 of a hydraulic cylinder 49 provided tothe turning machine 38 b is pushed against a portion of the outer sidesurface of the rotor near the inner diameter. Concave portions areformed in portions opposing to respective studs 9 by a part of theannular piston 66 to prevent interference between these studs 9. Withthis arrangement, the wheel bearing unit 5 is held between the top endsurface of the annular piston 66 and the top end surface of the chuck39. Also, the top end portion of the rotating shaft 40 a of the turningmachine 38 b is inserted into the inside of the spline hole 20 providedto the hub 8 b from the inside in the axial direction, and then isspline-engaged with the female spline portion 53 of the spline hole 20.In this situation, both side surfaces and the outer peripheral surfaceof the rotor 2 are finished into the predetermined shape and dimensionby putting the precision machining tools 41 a to 41 c to the concernedportions while rotating/driving the rotating shaft 40 a.

In the case of the present embodiment, like the case of the seventhembodiment shown in above FIGS. 13 and 14, the swing of the brakingfriction surface provided to both side surfaces of the rotor 2 can besuppressed satisfactorily not to increase particularly a productioncost, and also the chips generated during the turning process applied tothe both side surface of the rotor 2 can be prevented from adhering tothe inner side surface of the encoder 28. Also, in the case of thepresent embodiment, in applying the turning process to the both sidesurface of the rotor 2, the wheel bearing unit 5 is held between the topend surface of the annular piston 66 and the top end surface of thechuck 39. For this reason, unlike the case in the above seventhembodiment, there is no need to couple the rotor 2 and the rotary flange13 by the tentatively setting screws during the turning process. In thecase of the present embodiment, the top end portion of the rotatingshaft 40 a of the turning machine 38 b is inserted into the inside ofthe spline hole 20 provided to the hub 8 b from the inside in the axialdirection. But this top end portion may be inserted into the inside ofthe spline hole 20 from the outside in the axial direction.

Also, in the case of the present embodiment, since the phases of the hub8 b and the rotor 2 in regarding to the circumferential direction can berestricted uniquely, their phases in regarding to the circumferentialdirection can be restored into the state prior to the disassemblywithout fail even though the hub 8 b and the rotor 2 are disassembled inthe repair shop, or the like and then reassembled. Therefore, the swingof both side surfaces of the rotor 2 can be suppressed small firmlyafter the reassembling.

Also, in the case of the present embodiment, because the reinforcingmember 42 (see FIG. 13, etc.) to which the elastic member 43 is coupledis not fitted/fixed into the inner peripheral surface of the inner endportion of the outer ring 6, no seal ring is present between the innerperipheral surface of the inner end portion of the outer ring 6 and theouter peripheral surface of the inner end portion of the inner ring 16.In operation of such wheel bearing unit of the present embodiment, thewheel bearing unit 5 is fitted to the knuckle 3 and also the splineshaft 22 (see FIG. 21) constituting the constant velocity joint 21 isinserted into the spline hole 20. Then, in this condition, a sealingstructure is provided between a part of the constant velocity joint 21and the inner end portion of the knuckle 3. With such arrangement,although no seal ring is present between the inner peripheral surface ofthe inner end portion of the outer ring 6 and the outer peripheralsurface of the inner end portion of the inner ring 16, the space inwhich the encoder 28 is provided can be sealed tightly from the outside.Also, in this case, the sensing portion of the rotation speed sensoropposing to the encoder 28 can be sealed tightly from the outside.

Since other structures and operations are similar to those in theseventh embodiment shown in above FIGS. 13 and 14, their redundantexplanation will be omitted herein by affixing the same referencenumerals to like portions respectively.

Next, FIGS. 17 and 18 show a ninth embodiment of the present invention,which also corresponds to claims 2, 3, 5, and 6. In the case of thepresent embodiment, a pair of inner rings 16 a, 16 b are fitted/fixedonto the outer peripheral surface of the middle portion of the hub 8 b,and also the inner ring raceways 14 a, 14 b are formed on the outerperipheral surfaces of the inner rings 16 a, 16 b respectively. Also, apair of seal rings 19 a, 19 b to seal tightly the internal space 26 inwhich a plurality of balls 17, 17 are provided are provided between theouter peripheral surfaces of the end portions of the inner rings 16 a,16 b and the inner peripheral surfaces of both end portions of the outerring 6. Also, in the case of the present embodiment, when the turningprocess is applied to both side surfaces of the rotor 2 (see FIG. 14,etc.) fixed to the rotary flange 13 provided to the hub 8 b, a cover 30e is fitted/fixed into the inner end portion of the hub 8 b. This cover30 e is formed by injecting a synthetic resin such as polyethyleneterephthalate (PET), or the like by means of the injection molding, orthe like. The cover 30 e has the fitted cylinder portion 50 formed likethe bottomed circular cylinder, and the pressing collar portion 51provided to the middle portion of the outer peripheral surface of thefitted cylinder portion 50 and formed like the outward-directed flange.Also, plural locations (four locations in the illustrated case) of thefitted cylinder portion 50 in the circumferential direction are expandedtoward the outer diameter side over an almost full length along theaxial direction, and thus the projected portions 52, 52 are provided toplural locations in the circumferential direction. Also, a diameter of acircumscribed circle of these projected portions 52, 52 in their freestate is set slightly larger than an inner diameter of the innerdiameter portion of the spline hole 20 provided to the hub 8 b, whichgets out of the area in which the female spline portion 53 is formed.Also, a cylinder portion 54 is provided on the outer peripheral edgeportion of the pressing collar portion 51 to extend in the axialdirection, and also a taper portion 67 whose diameter is increasedgradually toward the top end edge is provided to the top end portion ofthe cylinder portion 54. Also, a latching collar portion 55 formed likethe outward-directed flange is provided to the outer peripheral surfaceof the base end portion (the right end portion in FIG. 17) of the fittedcylinder portion 50.

In applying the turning process to both side surfaces of the rotor 2,first respective constituent members of the wheel bearing unit which isin a state that the rotor 2 is not coupled yet are assembled, and alsothe fitted cylinder portion 50 of the cover 30 e is fitted/fixed intothe inner end portion of the spline hole 20 provided to the hub 8 b viaa plurality of projected portions 52, 52 by means of the smallinterference fit. Also, a portion of the outer side surface of thepressing collar portion 51 near the inner diameter is pushed against theend portion of the caulked portion 24 provided to the inner end portionof the hub 8 b, and also the top end edge of the taper portion 67provided to the portion of the pressing collar portion 51 near the outerdiameter is pushed against the inner end surface of the outer ring 6.Then, the wheel bearing unit is fitted to the turning machine 38 a (seeFIG. 14, etc.) in a state that the portion of the rotor 2 near the innerdiameter is fixed to the rotary flange 13 provided to the outerperipheral surface of the hub 8 b by the tentatively setting screws 35(see FIG. 14). Also, the top end portion of the rotating shaft 40 a (seeFIG. 14, etc.) of the turning machine 38 a is inserted into the insideof the spline hole 20 from the outside in the axial direction, and thenis spline-engaged with the female spline portion 53 of the spline hole20. In this situation, the turning process is applied to both sidesurfaces of the rotor 2 while rotating/driving the rotating shaft 40 a.Also, because the outer ring 6 is turned around the hub 8 b in theturning process, the top end edge of the taper portion 67 provided tothe cover 30 e fixed to this hub 8 b is slid on the inner end surface ofthe outer ring 6 and thus a frictional resistance is generated at thesliding portion. In the case of the present embodiment, in order tosuppress such frictional resistance, a thickness of the top end portionof the taper portion 67 is set smaller than 0.3 mm or less.

As described above, in the case of the present embodiment, the spacebetween the inner peripheral surface of the inner end portion of theouter ring 6 and the outer peripheral surface of the inner end portionof the hub 8 b is sealed tightly by the cover 30 e during the turningprocess. Therefore, it can be prevented that the chips generated in theturning process adhere to the inner side surface of the encoder 28.Also, an operation of removing the cover 30 e from the hub 8 b beforethe wheel bearing unit is fitted to the suspension system can be easilycarried out by the operator who pinches the portion projected from theinner end surface of the hub 8 b in the base half portion (the righthalf portion in FIG. 17) of the fitted cylinder portion 50 constitutingthe cover 30 e.

Also, in the case of the present embodiment, because the latching collarportion 55 is provided to the outer peripheral surface of the base endportion of the fitted cylinder portion 50, automation of the operationof removing the cover 30 e from the hub 8 b can be readily realized. Forexample, when the arm of the assembling robot (not shown) is movedtoward the inner end side of the hub 8 b while grasping the latchingcollar portion 55 with fingers of the assembling robot, the cover 30 ecan be removed easily from the hub 8 b. If the assembling robot toperform such operation is employed, the automation of the operation ofremoving the cover 30 e from the hub 8 b can be achieved.

Also, in the case of the present embodiment, the fitted cylinder portion50 of the cover 30 e is fitted/fixed into the inner end portion of thespline hole 20 via a plurality of projected portions 52, 52 during theturning process applied to both side surfaces of the rotor 2. Therefore,a dimensional tolerance of the inner diameter of the inner end portionof the spline hole 20 can be set large like 0.2 mm. Thus, even when theprocessed inner diameter of the inner end portion of the spline hole 20is formed smaller than a normal dimension, the fitted cylinder portion50 can be detachably attached easily to the spline hole 20 by a smallforce.

Since other structures and operations are similar to those in theseventh embodiment shown in above FIGS. 13 and 14, their redundantexplanation will be omitted herein by affixing the same referencenumerals to like portions respectively.

Next, FIG. 19 shows a tenth embodiment of the present invention, whichalso corresponds to claims 2, 3, 5, and 6. In the case of the presentembodiment, an insertion hole 56 that passes through from the outerperipheral surface to the inner peripheral surface is formed in a partat a circumferential section of a stationary flange 12a provided to theouter peripheral surface of the inner end portion of an outer ring 6 b.In operation of the wheel bearing unit, a circular cylinder portionconstituting the rotation speed sensor (not shown) is inserted into theinside of the insertion hole 56. Also, in the case of the presentembodiment, when the turning process is applied to both side surfaces ofthe rotor 2 (see FIG. 14, etc.), the outer peripheral surface of thecaulked portion 24 provided to the inner end portion of the hub 8 b isisolated from the inner peripheral surface of the inner end portion ofthe outer ring 6 b by a cover 57 and also the insertion hole 56 isclosed by a stop plug 61. The cover 57 is formed like an annular ring asa whole to have an almost

-shaped cross section. Also, a collar portion 59 formed like theoutward-directed flange is provided to a top end edge portion of anouter-diameter-side cylinder portion 58 constituting the cover 57. Suchcover 57 is fitted to the hub 8 b by fitting an inner-diameter-sidecylinder portion 60 provided to the inner peripheral edge portion intothe inner end portion of the hub 8 b before the turning process isapplied to both side surfaces of the rotor 2. In this state, the outerperipheral edge of the collar portion 59 provided to the cover 57 isopposed closely to the inner peripheral surface of the inner end portionof the outer ring 6 b via a small clearance and the outer side surfaceof the collar portion 59 is opposed closely to the inner side surface ofthe encoder via a small clearance. Then, the space in which the encoder28 is provided is isolated from the outside.

Also, the stop plug 61 is formed by coupling concentrically alarge-diameter-side cylinder portion 62 provide to its base half portionto a small-diameter-side cylinder portion 63 provided to its top halfportion via a stepped portion 64. Also, an opening of a top end portion(lower end portion in FIG. 19) of the small-diameter-side cylinderportion 63 is closed by a bottom plate portion 65. When thesmall-diameter-side cylinder portion 63 is fitted into the insertionhole 56 and also one side surface of the stepped portion 64 is broughtinto contact with the peripheral portion of the opening end of theinsertion hole 56 on the outer diameter on the outer peripheral surfaceof the stationary flange 12 a, such stop plug 61 closes the insertionhole 56 before the turning process is applied to both side surfaces ofthe rotor 2.

In the case of the present embodiment constructed as above, because theinsertion hole 56 provided to a part of the outer ring 6 b is stopped bythe stop plug 61 during the turning process applied to both sidesurfaces of the rotor 2, it can be prevented that the chips generated inthe turning process enter into the space, in which the encoder 28 isprovided, through the insertion hole 56. As a result, not only the spacebetween the inner peripheral surface of the inner end portion of theouter ring 6 b and the outer peripheral surface of the inner end portionof the hub 8 b can be closed by the cover 57 but also the adhesion ofthe chips onto the inner side surface of the encoder 28 can beprevented, so that an improvement of a sensing performance of therotation speed sensor that is opposed to the encoder 28 can be achieved.

Since other structures and operations are similar to those in the ninthembodiment shown in above FIGS. 17 and 18, their redundant explanationwill be omitted herein by affixing the same reference numerals to likeportions respectively.

Next, FIG. 20 shows an eleventh embodiment of the present invention,which corresponds to claims 2 and 5. In the case of above embodiments,the wheel bearing unit has a structure in which its inner ring isrotated. In contrast, in the case of the present embodiment, the wheelbearing unit 5 has a structure in which its outer ring is rotated. Inother words, in the case of the present embodiment, an outer ring 6 c isused as the rotary ring that is rotated in operation and a pair of innerrings 16 a, 16 b arranged on the inner side of the outer ring 6 c areused as the stationary ring that is not rotated in operation. Also, theencoder 28 is coupled/fixed to the inner end surface of the outer ring 6c.

In such configuration of the present embodiment, the operation ofapplying the turning process to both end surfaces of the rotor 2 (seeFIG.14, etc.) is performed as follows. That is, first respectiveconstituent members of the wheel bearing unit before the rotor 2 iscoupled are assembled and also the portion of the rotor 2 near the innerdiameter is coupled/fixed to the outer side surface of the rotary flange13 provided to the outer peripheral surface of the outer end portion ofthe outer ring 6 c. Also, a cover 30 f is fitted/fixed onto the innerend portion of the outer ring 6 c. The cover 30 f is formed like anannular ring as a whole to have an almost

-shaped cross section, and a lip portion 68 is provided to its innerperipheral edge portion. Then, an outer-diameter-side cylinder portion69 constituting the cover 30 f is fitted/fixed onto the small- diameterstepped portion 29 provided to the inner end portion of the outer ring 6c. Also, a top end edge of the lip portion 68 provided to the cover 30 fis pushed against the inner end surface of the inside inner ring 16 bout of a pair of inner rings 16 a, 16 b. In this state, the space inwhich the encoder 28 is provided is isolated from the outside of thecover 30 f. Then, in this condition, the wheel bearing unit with theside surface of the rotor 2, to which the turning process is applied, isfitted to the turning machine (not shown). Also, the rotating shaftcoupled to the end portion of the chuck is turned in a state that a pairof inner rings 16 a, 16 b are fitted/fixed onto the fixed supportingshaft constituting the turning machine and also the portion of the outerperipheral surface of the outer ring 6 c near the inner end, which isdeviated from the portion onto which the cover 30 f is fitted, isclamped by the chuck of the turning machine. Then, in this condition,the turning process is applied to both side surfaces of the rotor 2 nearthe outer diameter by putting the precision machining tool to thesesurfaces, and thus both side surfaces are finished into thepredetermined shape and dimension. In the case of the wheel bearing unitmanufactured in this manner, a sensing performance of the rotation speedsensor (not shown) that is faced to the encoder 28 can be assuredsufficiently, and also the swing of the braking friction surfaceprovided to both side surfaces of the rotor 2 can be suppressedsatisfactorily.

In the case of above embodiments, the case where the rolling bearingconstituting the wheel bearing unit is the ball bearing in which theballs are used as a plurality of rolling elements is explained. However,the present invention is not limited to such configuration, and may beapplied to the case where the rolling bearing constituting the wheelbearing unit consists of other rolling bearings such as the rollerbearing in which the cylindrical rollers, the tapered rollers, or thelike are used as a plurality of rolling elements. Also, in the aboveembodiments, the case where the side surface of the rotary flange 13 orboth side surfaces of the rotor 2 are processes into the predeterminedshape and dimension by the turning process is explained. However, thewheel bearing unit of the present invention contains such aconfiguration that the side surface of the rotary flange or the brakingfriction surface of the braking rotating body is processed intopredetermined shape and dimension by applying other processing such asthe grinding process, the superfinishing process, or the like whileturning the rotary ring around the stationary ring.

The present invention is explained in detail with reference toparticular embodiments. But it is apparent for the skilled person thatvarious variations and modifications may be applied without departingfrom a spirit and a scope of the present invention.

This application is filed based on Japanese Patent Application (PatentApplication No. 2002-304934) filed on Oct. 18, 2002, and contentsthereof are incorporated herein by the reference.

INDUSTRIAL APPLICABILITY

The wheel bearing unit and the method of manufacturing the same of thepresent invention are constructed and operated as described above.Therefore, the rotation speed of the wheel can be sensed with goodperformance and also unpleasant noise and vibration generated in thebraking operation can be suppressed.

1. A method of processing a wheel bearing unit that includes astationary ring that has a stationary raceway on a stationary peripheralsurface and is not rotated in operation, a rotary ring that has a rotaryraceway on a rotary peripheral surface and is rotated in operation, aplurality of rolling elements provided between the stationary racewayand the rotary raceway, an encoder fixed to a part of the rotary ringand at least a part of the encoder is made of a permanent magnet, acover fixed on an opening portion of an axially inner end of thestationary ring and having an insertion hole for inserting a part of aholder of a sensor in operation, and a rotary flange provided to anouter peripheral surface of the rotary ring, wherein said rotary flangecouples/supports a braking rotating body on a side surface of the rotaryflange at least in operation, the braking rotating body having a brakingfriction surface against which a friction material is pushed in abraking operation, comprising: processing a portion of the wheel bearingunit or the braking rotating body into predetermined shape and dimensionin a state that the stationary ring, the rotary ring, and the pluralityof rolling elements are assembled together, wherein prior to theprocessing a space in which the encoder is provided is isolated from anoutside by fitting a stop plug to the insertion hole of the cover, andremoving the stop plug from the cover after the portion of the wheelbearing unit is processed into predetermined shape and dimension butbefore the wheel bearing unit is fitted to a suspension system.
 2. Amethod of manufacturing a wheel bearing unit set forth in claim 1,wherein the processing comprises processing the side surface of therotary flange into predetermined shape and dimension while rotating therotary ring around the stationary ring in the state that the stationaryring, the rotary ring, and the plurality of rolling elements areassembled together.
 3. A method of manufacturing a wheel bearing unitset forth in claim 1, wherein the processing comprises processing thebraking friction surface into predetermined shape and dimension whilerotating the rotary ring that couples/supports the braking rotating bodyaround the stationary ring in a state that the stationary ring, therotary ring, and the plurality of rolling elements are assembledtogether.
 4. A method of manufacturing a wheel bearing unit set forth inclaim 1, wherein the stationary ring is an outer ring that has an outerring raceway as the stationary raceway on an inner peripheral surface asthe stationary peripheral surface, and the rotary ring is a rotatingmember that is arranged on an inner diameter side of the outer ring andhas an inner ring raceway as the rotary raceway on an outer peripheralsurface as the rotary peripheral surface, and wherein the processingcomprises processing the side surface of the rotary flange provided toan outer peripheral surface of the rotating member into predeterminedshape and dimension while rotating the rotating member around the outerring in the state that the outer ring, the rotating member, and theplurality of rolling elements are assembled together.
 5. A method ofmanufacturing a wheel bearing unit set forth in claim 1, wherein thestationary ring is an outer ring that has an outer ring raceway as thestationary raceway on an inner peripheral surface as the stationaryperipheral surface, and the rotary ring is a rotating member that isarranged on an inner diameter side of the outer ring and has an innerring raceway as the rotary raceway on an outer peripheral surface as therotary peripheral surface, and wherein the processing comprisesprocessing the braking friction surface of the braking rotating bodyinto predetermined shape and dimension while rotating the rotatingmember around the outer ring in the state that the outer ring, therotating member, and the plurality of rolling elements are assembledtogether.